Recent content by string_656

well that's what I am not sure about. The book states that the "normal unit vector" is defined as N(t) = T'(t)/|T'(t)| where T(t) = r'(t)/|r'(t)| the textbook uses 1 example (its very brief about this topic), but it uses cos, and sin. so constantly differentiating them dosn't reduce it to...

umm ok?.. so r(t) = 2(t)i +4(t)j - 1(t)k so you went, r'(t) = 2 + 4 - 1 and... |r'(t)| = (sqrt(21) so T(t) = 2/(sqrt(21)i + 4/(sqrt(21)j - 1/(sqrt(21)k...? ... T'(t) = 0 |T'(t)| = 0 N(t) = 0?? Thanks for the help by the way.

unit mormal vector is given by N(t) = T'(t)/|T'(t)| where T(t) = r'(t)/|r'(t)|, and i think in this case r(t) = 2i +4j - 1k. so I am a bit stuck because it will just end up being zero?

Homework Statement Find unit normal vector to the surface z = 2xy at (2,1,4) Homework Equations - The Attempt at a Solution fx = 2y fx(2,1,4)=2 fy = 2x fy = 4 = (2,4,-1) is this correct? and in the right format?

Find the x-axis motion... so... cos 38 * 40 = 31.52 m/s.. now that never changes in ideal conditions...only in the y direction the velocity changes due to gravity.. now u no at some time its 24 degrees below horizontal.. the ball or what ever is still traveling at 31.52 metres/s in the x...

this is what i think you do... draw a triangle with 2m/s as the hyp and 0.5m/s as the adjacent. The opisite is the speed he will cross the river .. now calculate the angle of the triangle. it is about 75 degrees.. .. now u no the angle that he needs to cross at... draw another...

Homework Statement ^^^^ = resistor = 10 ohm <> = 3*Vab Dependent voltage. (the voltage equals 3 times Vab) 0 = voltage source 4 v (inderpendant) o = Inderpendant Current source 2 A |--^^^^---<>---------a + | + + - | 0 o Vab | -...

how do you determine whether a second order differential equation can be solved or not?

thanks repainted, lurflurf how could i rearange it so that its in a + ib form?

hey again, im have a problem with 1 of the questions I am doing. Z^3 = 2+2i, and it asks to solve for Z. does it want me to actually get a number for Z? or does it simply want me to write... z = (2+2i)^(1/3) but ^^^^ this seems way to easy

oh, ok thanks.

opps that didnt post right wouldnt i go z = ln(i-1)/(0 - i) *(0+i)/(0+i)

hmm ok .. just a question, when its iz = ln|i-1| wouldnt i go z = ln(i-1) * (0+i) (0 - i) * (0+i) because I am just remembering when you divide complex numbers that's all.

hmm ok so that gives... z = ln(i - 1)/i it can't be that easy? what about... since e^(iz) = cos(z) + isin(z) cos(z) + isin(z) = i - 1 Then how would i solve for Z?

.. does any 1 no how i could solve this?