Explain, in one or two sentences, why for every real when and are defined by the unit…

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

Problem

Explain, in one or two sentences, why

\sin^2\theta+\cos^2\theta=1

for every real

\theta

when

\sin\theta

and

\cos\theta

are defined by the unit circle.