Mathematics

Problem

Let

x(t)=\sin t

and

y(t)=\cos 2t

for

0<t\le 2\pi

. Which of the following lists all values of

t

in this interval where the curve has a horizontal tangent? a)

t=\dfrac{\pi}{2},\;\dfrac{3\pi}{2}

t=\dfrac{\pi}{2},\;\pi,\;\dfrac{3\pi}{2}

t=\pi,\;2\pi

t=\pi