Question

Find the exact value of the trigonometric function at the given real number?
- Sin (21pi/2)
- Cos (21pi/2)
- Cot (21pi/2)

Answer 1

\[\sin(21\pi /2 ) = (21\pi/2 )(180/\pi) = \sin(1890) = 1\]\[\cos(21\pi / 2) = (21\pi/2)(180/\pi) = \cos(1890) = 0\]\[\cot(1890) = 1/\tan(1890) =\cos(1890)/\sin(1890) = 0\]

All you have to do is convert the angle from radians to degree by multiplying the given angle with:

\[180/\pi\]

but if you want to convert from degree to radians then multiply by:

\[\pi/180\]

^_^