# Search results for query: *

1. ### MHB Tan(cos2x)

I'm not sure I understand
2. ### MHB Tan(cos2x)

tan(2 cos^-1(x)) I'm pretty sure 2 cos^-1(x) is the same as cos2x, the doubles formula, but from there I'm completely lost.
3. ### MHB Graph the function y=-1/2[cos(x+pi)+cos(x-pi)] and make a conjecture

I don't even know what a conjecture is y=-1/2[cos(x+pi)+cos(x-pi)]
4. ### MHB Express in terms of sine function of f(x)=sinx+cosx

f(x)=sinx+cosx getting really frustrated with my math teacher. gives us forumlas for things but then barely shows us how to use them if at all and then throws problems at that we have to make sense of ourself. why can't math teachers teach? anyway, the question is express f(x)=sinx+cosx in...
5. ### MHB Proving with addition and subtraction formulas: tan(x-y)+tan(y-z)+tan(z-x)=tan(x-y)tan(y-z)tan(z-x)

tan(x-y)+tan(y-z)+tan(z-x)=tan(x-y)tan(y-z)tan(z-x) I have redone this problem two or three times and all the steps just make my head spin. I've tried looking up tutorials online but they introduce things into the problem that we haven't been taught yet and that just confuses me more. Help!
6. ### MHB Find the square roots of 4*sqrt(3)+4(i)

No, i don't know what the right side means. - - - Updated - - - Actually I don' know what any of that means. Where did the 8 come from?
7. ### MHB Find the distance between points C and D if the height of the tree is 4m

So the question is...From point C on the ground level, the angle of elevation to the top of a tree is 30 degrees. From point D, which is closer to the tree, the angle of elevation is measured to be 45 degrees. Find the distance between points C and D if the height of the tree is 4m. I know...
8. ### MHB Find the angle between 2 vectors w=i+3j, vector v=<5, 2>

I know how to find the cos(theta) between two vectors but I do not know how to find the sin(theta). vector w=i+3j vector v=<5, 2>
9. ### MHB Find the square roots of 4*sqrt(3)+4(i)

So I have a study guide for my final which was written by a different professor from my actual professor. So I don't understand the question, I don't know if it's because my professor did not teach this or if the wording is different from what I'm used to: Find the square roots of 4*sqrt(3)+4(i)
10. ### MHB Express cos(2 tan^-1(x/4)) and sin(2tan^-1(x/4) as an algebraic expression in x

but its 2*tan^-1(x/4). Isn't that the same as 2*tan(theta)=x/4. So wouldn't I divide both sides by 2 and get x/8 and go from there?
11. ### MHB Area of iscoceles triangle

Side lengths are a=6, b=6, c=4. Find the area A=1/2*b*h I split the triangle in half to find the height. Since the base is 4, that divided the base into 2: 2^2+h^2=6^2 4+h^2=36 h^2=32 h=4*sqrt(2) =========== 1/2*4*4*sqrt(2)=area of 8*sqrt(2) Did I do this correctly? I do not have an...
12. ### MHB Triangle ABC has area 25*sqrt(3). if Angle BAC=30 degrees, find |AC|=|BC|=?

Triangle ABC has area 25*sqrt(3). if Angle BAC=30 degrees, find |AC|=|BC|=? the answer I got was 10*4th root(3) Is this correct? I am asking because someone other than my professor wrote the study guid for us for the final and I am not 100% sure what |AC|=|BC| means as my professor never...
13. ### MHB Express cos(2 tan^-1(x/4)) and sin(2tan^-1(x/4) as an algebraic expression in x

So my professor gave us a study guide for the final but no there is no answer key. Could someone check my answers please? Express cos(2 tan^-1(x/4)) and sin(2tan^-1(x/4) as an algebraic expression in x I got: cos(theta)=8*sqrt(x^2+64)/x^2+64 sin(theta)=x*sqrt(x^2+64)/x^2+64
14. ### MHB Evaluate cos 2(theta) and sin 2(theta)

Thank you! Looks like I had the right idea.
15. ### MHB Evaluate cos 2(theta) and sin 2(theta)

So my math professor gave us a study guide for the final but he's not aloud to give us the answers so I have no idea if my answers are correct or not. So if a few people could let me know what they got after trying this that would be great. If tan(theta) = -2[sqrt(2)], and theta is between 270...
16. ### MHB Find the sin angle between two 2d vectors

Tomorrow is my math test and I'm going over the study guide: I have vector U=<1, 3> and vector V=<5, 2> It says let theta be the missing angle between the two vectors. What is the cos(theta) and sin(theta)? I already know how to find the missing angle for cos(theta) but we never covered how...

Yes Thanks
18. ### MHB Convert polar equation sec(theta)=2 to rectangular equation

*Sigh* It's always so obvious when someone shows me the steps but I have the hardest time figuring it out on my own. thanks
19. ### MHB Convert polar equation r= 1/1+sin(theta) to rectangular equation

The equation is: r= 1/1+sin(theta) I know the answer is supposed to be: x^2+y^2=(1-y)^2 I can't figure out the steps to get to the answer.
20. ### MHB Convert polar equation sec(theta)=2 to rectangular equation

My professor gave us a study guide with the solutions: The equation is: sec(theta)=2 I am supposed to convert it to a rectangular equation. I know the answer is going to be y^2-3(x)^2=0 I don't know how to get to the answer he gave us.
21. ### MHB DeMoivre's Theorem express (sqrt(2)/2 + sqrt(2)/2 i)^8 in a+bi form

So the question is: express (sqrt(2)/2 + sqrt(2)/2 i)^8 in a+bi form I know r=1 and tangent=pi/4 Using the theorem i get 1(cos (2pi) +i*sin (2pi)) which becomes 1(1*i)=1*i however WebAssign says this is incorrect. I've also tried "0+1i" and just "i" What am I doing wrong?
22. ### MHB Convert r=7cos(theta) into a rectangular equation

So we're learning to plot polar equations, which easy enough. But I got a question in the homework that wasn't covered in class: Convert r=7cos(theta) into a rectangular equation. Use x and y values. I know how to convert when it's x=r*cos(theta) or y=r*sin(theta) and r and theta is given. But...
23. ### MHB Convert another equation x^2+y^2=4 to polar form

got it! thanks!
24. ### MHB Convert equation 8x=8y to polar form

Yeah I shot him a message, I just hope he gets back to me in time, assignment is due tonight at midnight
25. ### MHB Convert equation 8x=8y to polar form

It still didn't take it
26. ### MHB Convert another equation x^2+y^2=4 to polar form

x^2+y^2=4 I have so far: (r^2)cos^(theta)+(r^2)sin(theta)=4 Idk what I'm supposed to do from here
27. ### MHB Convert equation 8x=8y to polar form

Yes, it didn't take it
28. ### MHB Convert equation 8x=8y to polar form

I tried inputting pi/4 and 5pi/4, but it doesn't want an answer, it wants the question converted to a polar equation.
29. ### MHB Convert equation 8x=8y to polar form

Nope, no typo. I also tried cos(theta)=sin(theta). Then I thought I need to get the r alone and I got r=r*tan(theta)
30. ### MHB Convert equation 8x=8y to polar form

Convert the equation to polar form 8x=8y I thought it would be 8*r*cos(theta)=8*r*sin(theta) Said it was incorrect then I thought I needed to divide by 8 to remove it, giving me: r*cos(theta)=r*sin(theta) But that was also incorrect and now I am stuck
31. ### MHB Use double or half angle formulas

Ok, So with this problem it says to use double angle or half angle formula. I have the formulas in my notes just not sure how to apply them to the problem I feel like I should be using the double formula though. Here's the problem: cos(2*theta)+sin^2=0
32. ### MHB Solve sec(3θ)−2=0

I know, I included both
33. ### MHB Solve sec(3θ)−2=0

Ok I figured it out, I had to include 5*pi/9 +2/3*pi*k
34. ### MHB Solve sec(3θ)−2=0

Ok, I get how you solved it, however when I input it the computer tells me it's wrong.
35. ### MHB Solve sin(x)-1=cos(x)

I did that but I'm still lost. My professor emailed me back, said to square both sides the squared cos can be turned into sines using the pythagorean theorem identity. Which doesn't make sense to me because the pythagorean theorem identity still has cosines in it? Sorry I'm replying so late.
36. ### MHB Solve sec(3θ)−2=0

Ummm... thanks but can you fix this so I can read it more easily?
37. ### MHB Solve sin(x)-1=cos(x)

I don't know what you mean.
38. ### MHB Solve sec(3θ)−2=0

The secant is not cubed, it's sec 3*(theta)
39. ### MHB Solve sec(3θ)−2=0

Before I post the question I need to vent. I've about had it with my math professor. He isn't showing us how to solve problems that keep popping up in the math homework and I am 100% lost most of the time. Ok I'm done. The question is sec 3(theta)-2=0
40. ### MHB Solve sin(x)-1=cos(x)

So the problem is sin(x)-1=cos(x) and I don't know how to do this one.
41. ### MHB Evaluating cos((1/2)arccos(x))

I don't know how to solve this, we didn't really cover any problems like this in class cos(1/2*cos^-1*x) This is due tonight online and would like help please.
42. ### MHB Law of Cosines: Solve for angles given the sides of triangle

Answer wasn't correct for angle A but it was correct for angle c. Sorry it was sideways, that was just how it uploaded. Still not sure why I can't find angle A though when a=21 is opposite of angle A.
43. ### MHB Law of Cosines: Solve for angles given the sides of triangle

I've attached the problem and my work. When I enter cos^1(6.890625) I get an error, but 6.9 is also not the answer and Does Not Exist is also not an acceptable answer. So where I am going wrong with this?
44. ### MHB Investment word problem

Re: Word investment problem Ooooh...ok I see what I did wrong. Thank you!
45. ### MHB Investment word problem

Re: Word investment problem Could someone maybe try it and see what they get?
46. ### MHB Investment word problem

Re: Word investment problem I got 6700 for total amount invested and 2200 for unknown additional amount and it's still saying it's incorrect (online homework program)
47. ### MHB Investment word problem

Re: Word investment problem I have no idea lol, the setup is what I came up with, we were just given the word problem. So I know my setup is wrong, but I don't know why or how to set it up correctly.
48. ### MHB Investment word problem

So I have an investment word problem that I have tried multiple times and have not been able to get the right answer. "If Ben invests \$4500 at 4% interest per year, how much additional money must he invest at 5.5% annual interest to ensure that the interest he receives is 4.5% of the total...
49. ### MHB Rational Roots Theorem

Well at least I know I did it right, thanks!
50. ### MHB Rational Roots Theorem

I don't know how to show it on here but I'll do the best I can. So we have 4x^3-18x+4/ (x-2) In synthetic division I used 4 0 -18 4 to divide by 2. I got 4x^2+8x-2 with remainder of 0. I applied the quadratic formula to 4x^2+8x-2 and got the answer -2 +/- sqrt{6} all over 2