Mathematics

Problem

The curve is defined by

x=\sin t

and

y=\cos t

for

0<t<\pi

. The tangent line at

t=\pi/4

is perpendicular to the tangent line at which of the following parameter values? a)

\dfrac{\pi}{2}

\dfrac{3\pi}{4}

\dfrac{\pi}{6}

\dfrac{5\pi}{6}