Chapter 5 - Trigonometric Identities - Section 5.2 Verifying Trigonometric Identities - 5.2 Exercises - Page 210: 102a

Write an expression for $P$ that involves the cosine function. $$P=16k\cos^2(2\pi t)$$

$$y=4\cos(2\pi t)$$ $$P=ky^2$$ Write an expression for $P$ that involves the cosine function. We replace the formula of $y$ into the formula of $P$. $$P=ky^2$$ $$P=k[4\cos(2\pi t)]^2$$ $$P=k[16\cos^2(2\pi t)]$$ $$P=16k\cos^2(2\pi t)$$