Question

circle x^2 +y^2 = 1.

r(t) = (sint)i +(cost)j
at both pi/4 and pi/2
Find velocity & acceleration

Thx!

Answer 1

What you have is a vector equation. i and j are unit vectors.

velocity = v = dr/dt
= cos t *i - sin t*j
acceleration = dv/dt
= -sin t*i -cos t*j
= -r
Plug in the values t = pi/4 and also t = pi/2 for the answers they are looking for.