Module 4: Now You Try III

Suppose $0 < y < \frac{π}{2}$ $0\; <\; y\;<\; \frac{\pi}{2}$ is given and that $\cos (y) = 2 x$ $\cos(y)=2x$ . Compute $\sin (y)$ $\sin(y)$ .

Solution:

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We start by drawing a right triangle with angle

y

$y$ and

\cos (y) = 2 x

$\cos(y)=2x$ .

The missing side is

\sqrt{1 - 4 x^{2}}

$\sqrt{1-4x^2}$ , therefore $LaTeX: \sin(y)=\sqrt{1-4x^2}$

$\sin(y)=\sqrt{1-4x^2}$ .