Question

Given the following graph of y = cos(θ+π/2) from 0 ≤ θ ≤ 2π:

a) For what value(s) of θ does the instantaneous rate
of change appear to equal 0?

b)For what value(s) of θ does the instantaneous rate
of change reach its maximum? Its minimum?

Answer 1

note that cos(θ+π/2) = -sinθ

(a) the max/min occur when -sinθ = ±1. Where does that happen?
(b) the slope is steepest when -sinθ = 0. Where's that?

Just look at the graph to confirm your choices.