Show that ^2 5^ + ^2 10^ + ^2 15^ + + ^2 90^ = 9 1 2

MATHEMATICS · Subjective · A Level · Mathematics · Trigonometry · Trigonometry

Problem

Show that

\sin^2 5^\circ + \sin^2 10^\circ + \sin^2 15^\circ + \dots + \sin^2 90^\circ = 9\frac{1}{2}