Suppose an object moves in an elliptical orbit parametrized by

x = 2 cos t and y = 7 sin t, where t ≥ 0.

Determine the value of the velocity at the indicated times:
v(pi/4)
v(pi/2)

Question

Suppose an object moves in an elliptical orbit parametrized by 

x = 2 cos t and y = 7 sin t, where t ≥ 0. 

Determine the value of the velocity at the indicated times: 
v(pi/4)
v(pi/2)

anonymous · Answer

for v(pi/4) I got 2 (which was wrong) by taking the sqrt((-2sin(pi/4))^2) + (2cos(pi/4))^2)).. ifyou have any idea where I went wrong, I would appreciate the help!!

anonymous · Answer

Velocity is a vector.

anonymous · Answer

I don't think you need to find the magnitude.

anonymous · Answer

$$
v_x=-2\sin t\
v_y=7\cos t
$$

anonymous · Answer

now to find magn. take sqrt of ((-2sint)^2+(7cost)^2)

anonymous · Answer

subst. t =pi/4 or pi/2