# Thread: Find Exact Value without Calculator

1. ## Find Exact Value without Calculator

Hello all,

I'm trying to determine how one would solve the below problem without a calculator or a table. None of the angles are ones I easily recognize - how can I solve it?

These are given in degrees, not Rads

$sin(81 + 21)$

Thank you for all of your brilliant help!

2. ## Re: Find Exact Value without Calculator

\displaystyle \begin{align*}\sin{\left(102^{\circ}\right)} &= \sin{\left(6^{\circ} + 36^{\circ} + 60^{\circ}\right)}\end{align*}

You will need to use the angle sum identity at least twice. Also Exact trigonometric constants - Wikipedia, the free encyclopedia will help you.