Intersection Definition and 688 Threads

  1. T

    Prove Intersection of Subgroups of G is Normal Subgroup

    Homework Statement Suppose that a group G has a subgroup of order n. Prove that the intersection of all subgroups of G of order n is a normal subgroup of G. Homework Equations The Attempt at a Solution I know that I need to do the following: Let S be the set of all subgroups of...
  2. A

    Intersection points of two lines in two-space

    Homework Statement Show that the following pairs of lines intersect. Determine the coordinates of the point of intersection. L1: r= (-3,-1) + t(3,4) L2: r= (6,2) + s(3,-2) Homework Equations ? The Attempt at a Solution I know that eventually the two lines will reach the...
  3. A

    Tangent line of curve of intersection

    Homework Statement Find the parametric equations of the line tangent to the curve of intersection of the paraboloid z = x² + y² and the ellipsoid 4x² + y² + z² = 9 at the point ( -1, 1, 2 ). Homework Equations Probable use of the gradient vector (as this is the chapter we are in)...
  4. N

    Points of intersection with polar equations

    Homework Statement I have to find all of the points of intersection of the curves... r2 = sin(2θ) r2 = cos(2θ) The Attempt at a Solution sin(2θ) = cos(2θ) 2sinθcosθ = cos2θ - sin2θ 2sinθcosθ - cos2θ = -sin2θ cosθ(2sinθ - cosθ) = -sin2θ This is where I'm having a problem, I'm...
  5. S

    HelpGiven a common intersection point, create 3 different planes

    Homework Statement Given a common intersection point (3,4,5), find 3 different planes. Homework Equations None The Attempt at a Solution What I did is let a1x+a2y+a3z=a b1x+b2y+b3z=b c1x+c2y+c3z=c 3=Dx/D 4=Dy/D 5=Dz/D I set D=2, therefore Dx=6 Dy=8 Dz=10...
  6. N

    Intersection pts of polar equations

    Homework Statement I have to find the area of the region that lies inside the curves: r = sin(θ) r = sin(2θ) The Attempt at a Solution I'm assuming the first step would be to find the points of intersection so I know WHERE to integrate from/to, so I set the equations equal to each...
  7. R

    Finding the Centre and Intersection of Circle X2 + y2 + 4x – 16y + 18 = 0

    Homework Statement Find the centre of circle X2 + y2 + 4x – 16y + 18 = 0, show it's radius is 5√2 and find the co-ordinates where it is intersected by y = 3x - 6 Homework Equations The Attempt at a Solution X2 + y2 + 4x – 16y + 18 = 0 by completing the square using X2 + 2px = (x...
  8. D

    Point of intersection of two lines

    Homework Statement Find the point of intersection of two lines x = -9 + 5t y = 1 + t z = 10 - 4t and x = -2 -3t y = 5 + 2t z = 5 + 3t Homework Equations N/A The Attempt at a Solution I have read that you should set two of the equations equal to find the value of t, and...
  9. T

    What are the possible solutions for the inequality |2x-1|+|x+2|\geq 4x?

    Homework Statement |2x-1|+|x+2|\geq 4x Homework Equations The Attempt at a Solution For x<-2 , -(2x-1)-(x+2)\geq 4x x\leq -\frac{1}{7} For x\geq \frac{1}{2} 2x-1+x+2\geq 4x x\leq 1 For -2 \leq x < \frac{1}{2} , -(2x-1)+x+2\geq 4x x\leq \frac{3}{5} after...
  10. S

    Dimension of intersection of U and V

    Homework Statement Prove true: For any subspaces U,V of R^n dim(U intersect V) <= min(dim(U), dim(V)) Homework Equations Min(a,b) = the minimum value of A and B The Attempt at a Solution I know this statement is true however I can't quite figure out where to start on how to...
  11. J

    Proving/Disproving: U and V Intersection in Rn

    So for my homework I have to prove (or disprove) this statement: If U, V are two subspaces of Rn then U \cap V \neq \phi. I just want to make sure; \phi is the null set right? The set with nothing in it?
  12. A

    Parametric Equation of a Line from the intersection of two planes

    Homework Statement Find the parametric equation for a line of intersection of these two planes x+2y+3z=0 4x+5y+6z=5 Homework Equations Normal to plane 1= <1,2,3> Normal to plane 2= <4,5,6> The Attempt at a Solution I know the way to do this problem is to take cross product of...
  13. D

    Proof with intersection of subspaces

    Homework Statement Suppose L, M, and N are subspaces of a vector space. (a) Show that the equation L \cap (M+N) = (L \cap M)+(L \cap N) is not necessarily true. (b) Prove that L \cap (M+(L \cap N))=(L \cap M) + (L \cap N) Homework Equations N/A The Attempt at a Solution...
  14. V

    Maximum Speed - T-shaped intersection

    A couple of months ago I was pulled over by a police officer for running a stop sign. The officer claimed I "plowed right through" the stop sign. I honestly had no idea what he was talking about but wasn't about to argue with a cop. I realized after going back to check the intersection after...
  15. L

    How to find the intersection of two vectors

    L1: r(t) = (-5 + 2t)i + (5 + t)j L2: r(t) = (3 + 4t)i + (4 - 8t)j I know that they are perfendicular but how do I go about finding the point of intersection?
  16. T

    Find the intersection of a particle and a plane in R3

    Homework Statement The starting position of a particle in R3 is (1,1,1) and it's traveling with constant velocity (2,-1,1). Where does it hit the plane {(x,y,z)|x - 2y + z = 4}. And find the angle between the path of the particle and the plane. Homework EquationsThe Attempt at a Solution
  17. L

    Intersection of simply connected

    Hi everybody! I have a question, if I have A and B simply connected subspaces of a geodesic space X, what can be said about their intersection? When is it simply connected? Are there rules for this? I need to prove it in a special case, but I am not able to do it and I was wondering if...
  18. H

    Finding the Intersection of Two Planes in Parametric Form

    Homework Statement Consider the intersection between the following two planes given in parametric form: P1 : x = [2, 4. 3] + s1[1, 2, 1] + s2[2, 5, 4] P2 : x = [1, 0, -5] + t1[3, 8, 7] + t2[2, 1, -5] Find the intersection of the two planes as a line in parametric form. Homework...
  19. D

    How Do You Find the Point of Intersection for These Equations?

    Homework Statement Find the point of intersection Homework Equations Equation 1 y=1/5(2)4x-7 Equation 2 y=1/10(1/2)9-3x The Attempt at a Solution Made them equal each other got rid of the 1/5 one one side and it made the 1/10 turn into 1/2 and now i don't know...
  20. T

    Sum and intersection of anihalator spaces

    Homework Statement prove that (U\bigcapW)^{\circ}=W^{\circ}+U^{\circ} First prove That (U\bigcapW)^{\circ}\supseteqW^{\circ}+U^{\circ} Take any f\in (U\bigcap W)^{\circ} Then it is easy to see that for any f\in (U\bigcap W) f(v) =0 but since v\in U and v \in W then f \in...
  21. T

    General questions about intersection of subspaces

    Hey Guys. I have some questions about vector spaces, I would really apreciate if somone could read this and let me know if I understand things or not, and if not let me know where I have it wrong. I am having a lot of trouble UNDERSTANDING how to find the intersection of two vector spaced...
  22. H

    Calc III: sphere & plane intersection.

    Consider the intersection of the sphere (x-3)^2+(y+2)^2+(z-1)^2=13 with the plane x+y=0 a) This intersection should be a familiar curve. Describe the curve. b) Substituing x=-y or y=-x into the equation of the sphere does not give this curve. Explain the difference. I know that the...
  23. J

    Need Help Finding Points of Intersection

    Homework Statement y=x-x^3 y=0 Must find intersection points by way of the x-axis Homework Equations The Attempt at a Solution I know you have to set them equal to each other i just do not know what to do from there.
  24. C

    Intersection point between a line with slope m and f(x)

    Homework Statement f(x) = 2x2-5x-12 is given; part a: find derivative of f(x) using first principles, part b: find the rate of change of f(x) at x=1, part c: the points at which the line through (1, -15) with slope m cuts the graph of f(x), part d: the value of m such that the points of...
  25. J

    Angle of intersection: polar versus cartesian

    Is it correct that the angle of intersection of two curves is the same in x,y coordinates as in r,theta coordinates? If so, why is this?
  26. M

    Equation of plane containing the intersection of two planes

    Homework Statement Find an equation of the plane that passes through the point (-1,2,1) and contains the line of intersection of the planes x + y - z = 2 and 2x - y + 3z = 1 Homework Equations Equation of a plane: a(x-x0) + b(y-y0) + c(z-z0) = 0 The Attempt at a Solution n1 =...
  27. T

    Solve Math Puzzle: Proving Nonemptiness of Intersection

    Here's a math problem that's giving me a head ache (though to some of you it might seem to be quite trivial) r,s\in N^\ast , r+1\leq s ; |A_i|=r, \forall i\in \{1,2,...,s\} the intersection of any r+1 of sets A_i is nonempty [1] prove that \bigcap_{i=1,s} A_i \neq \emptyset [C]...
  28. T

    What Values of K Make the Intersection of Two Graphs Positive?

    the graph of y=kx+3 intersects the graph of y=x^2 +8x at two distinct points for 'k 'equals what? to be honest I do not know where to start
  29. P

    Tangent vector to curve of intersection of 2 surfaces

    Homework Statement Find the tangent vector at the point (1, 1, 2) to the curve of intersection of the surfaces z = x2 + y2 and z = x + y. Homework Equations The Attempt at a Solution I haven't started the problem, because I'm not sure what the first thing to do is. Do I have to parametrize...
  30. P

    Tangent line of the curve of intersection of two surfaces

    How do I find this?
  31. S

    Proofs of subspaces in R^n (intersection, sums, etc.)

    Homework Statement Let E and F be two subspaces of R^n. Prove the following statements: (n means "intersection") If EnF = {0}, {u1, u2, ..., uk} is a linearly independent set of vectors of E and {v1, v2,...vk} is a linearly independent set of vectors Note: Above zero denotes the...
  32. M

    Finding the Intersection of Two Circles: A Challenge

    hi everyone ! we have two circles that doesn't have intersections now we want to find a point on each circle that the distance of this two points are 'k' please help me . . .
  33. V

    Finding the volume of a 3-dimensional spherical intersection

    If two spheres of radius 1 intersect each other so the surface of each sphere passes through the other’s center how could you find the exact volume of the intersection? It doesn't matter what kind of method, it could be double or triple integration, geometry, polar, cylindrical or spherical...
  34. I

    Finding the point of intersection between two vectors

    Homework Statement L1 passes through (1,-4,0) and (9,0,4) L2 passes through (2,-3,-1) and (4,-3,3) Do L1 and L2 intersect? If so, where? Homework Equations Parametric equations(?) The Attempt at a Solution A = (1,-4,0) B = (9,0,4) C = (2,-3,-1) D = (4,-3,3) AB =...
  35. P

    Parametrics - intersection and collision

    Homework Statement x1t= 2-cos(pi*t) y1t= 3+7sin(pi*t) x2t= 3t+2 y2t= -(7/15)(3t+1)2 + 157/15 Find points of intersection and collision Homework Equations above? The Attempt at a Solution Well, to find the intersection I think I need to eliminate the parameters for both...
  36. T

    Intersection of probabilities.

    Hello, I need help with this problem: A: 67,000 Purchasing managers that are male B: 33,000 purchasing managers that are female C: 245,000 financial managers that are male D: 150,000 financial managers that are female Out of these 495.000 individuals , what is the probability that a...
  37. A

    Point and Circle intersection in 3 D

    Hi I need some support regarding a problem. I know the poistion of a point in 3D let say (sp,yp,zp) and I know the circle with Center (xc,yc,zc) having radius rc. My question is how to find the intersection point of the circle and a line in 3D. I know that we can find the POI in 2 D by...
  38. D

    Set notation (union and intersection)

    Homework Statement Find simpler notation for the two sets: A= \bigcup^{\infty}_{j=0}[j,j+1] and B= \bigcap_{j \in Z}(R minus\ (j,j+1)) Homework Equations The Attempt at a Solution Not really sure what it means by "simpler notation"... Does A=R since the union of...
  39. R

    Find some vector function whose image is the intersection of two surfaces

    Hi all, I'm quite new here, but it's been a while since I've been browsing through these forums for past answered questions for calculus and physics, but now comes the time where I'm the one needing help that's not been questioned yet. Homework Statement Find some* vector funcion r with...
  40. V

    Maple Approximating Line Intersection Equation with Maple

    I'm having a hard time creating a tidy equation to solve this seemingly simple problem. I have two points in standard 3D cordinate space, we'll call them C and D to be consistent with my work. The location of these points is given by (Ci,Cj,Ck) and (Di,Dj,Dk). I then have a third point, A...
  41. L

    Intersection of 2 subgroups is a subgroup?

    Homework Statement H and K are subgroups of G. Prove that H\capK is also a subgroup. The Attempt at a Solution For H and K to be subgroups, they both must contain G's identity. Therefore, e \in H\capK. Therefore, H\capK is, at least, a trivial subgroup of G. This was a test...
  42. C

    Lagrange Multipler and Max/Min point of intersection

    Homework Statement The plane 4x − 3y + 8z = 5 intersects the cone z^2 = x^2 + y^2 in an ellipse. Use LaGrange Multipliers to find the highest and lowest points on the ellipse. Homework Equations Lagrange Multiplier The Attempt at a Solution I guess I lack an understanding of...
  43. F

    Parametrization - circle defined by plane intersection sphere

    Show that the circle that is in the intersection of the plane x+y+z=0 and the sphere x2+y2+z2=1 can be expressed as: x(\vartheta) = (cos(\vartheta)-(3)1/2sin(\vartheta)) / (61/2)y(\vartheta) = (cos(\vartheta)+(3)1/2sin(\vartheta)) / (61/2)z(\vartheta) = -(2cos(\vartheta)) / (61/2) I'm really...
  44. C

    Proving complement of unions equals intersection of complements.

    Homework Statement Generalize to obtain (C1 U C2 U...U Ck)' = C1' intersect C2' intersect...intersect Ck' ' = complement Say that C1, C2,...,Ck are independent events that have respective probabilities p1, p2, ..., pk. Argue that the probability of at least one of C1, C2,...,Ck is equal to 1...
  45. D

    Intersection of a parabola with another curve

    Homework Statement For a any parabola with the equation y=kx^{2} I'm trying to find a curve that intersect every point of the parabola at right angles. Homework Equations For a perpendicular intersection the slope is -\frac{1}{m}The Attempt at a Solution I took the derivative and then took...
  46. R

    Find Intersection of Plane & Line, Does Line Lie in Plane?

    Homework Statement Find the point(s) of intersection (if any) of the plane and the line. Also determine whether the line lies in the plane. 2x-2y+z=12, x-\frac{1}{2}=-y-\frac{3}{2}=\frac{x+1}{2} Homework Equations 2x-2y+z=12 x-\frac{1}{2}=-y-\frac{3}{2}=\frac{x+1}{2} The...
  47. K

    Infinite union & infinite intersection

    I don't quite understand the meaning of "infinite union" and "infinite intersection". Is an infinite union ∞ U Ak k=1 being defined as a limit lim (A1 U A2 U ... U An) ? n->∞ How about an infinite intersection? Thanks!
  48. P

    Plot both sets and I want to highlight the intersection of A and B.

    I've two problems: Given are the two sets A = \left \lbrace (x_{0}, x_{1}, x_{2}, x_{3}) \in \mathbb{R}^{4} \mid x_{0}^{2} = \vec{x} \, ^{2}, x_{0} \geq 0 \right \rbrace and B = \left \lbrace (x_{0}, x_{1}, x_{2}, x_{3}) \in \mathbb{R}^{4} \mid (k_{0} - x_{0})^{2} = (\vec{k} -...
  49. M

    Plane through point and intersection of 2 other planes

    Homework Statement Find the plane that passes through the point (-1,2,1) and contains the line of intersection of the planes: x+y+z=2 2x-y+3z=1 The Attempt at a Solution First, I know that I need to find the line of intersection of the 2 planes. To do this, I used the cross product...
  50. S

    Intersection of a family of sets

    Homework Statement There is only a small issue that i am confused about... If we have a set \left(-\frac{1}{n},\frac{1}{n}\right), where n is a natural number. If we want to find the intersection of all such sets, my question is whether the result will be the set containing only...
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