The Goal

Find the exact value of:

The Mistake

Find the mistake:

(Roll the mouse over the math to see a hint in red)

The Correction

(Roll the mouse over the area above to see the correction in blue)

An Explanation

The words exact value often mean "don't use a calculator". You are expected to know the exact values of the trigonometric functions at all the nice angles. Visit Trigonometric Facts to help learn these values.