The Goal

Find

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 mistake is likely simply confusion with the inverse sine of 1/2. Cosine of π/3 is equal to 1/2. Students should learn the values of the inverse trigonometric functions at nice values - visit Trigonometric Facts to help learn these values.