CPM Homework Help : GC Problem 11-17

Examine the diagram of the triangle at right.

Right triangle labeled, hypotenuse, R, horizontal leg, X, vertical leg, Y, and angle opposite vertical leg, labeled, theta.

Write an equation representing the relationship between $x, y,\text{ and }r$ .
Hint (a):
Think of the Pythagorean Theorem.

Write an expression for $\sin\theta$ . What is $\sin\theta$ if $r = 1$ ?
Hint (b):
$\text{sin}\theta = \frac{\text{opp}}{\text{hyp}}$
Answer (b):
$\sin\theta = \frac{y}{r}\:\:\:\:\:\:\:\:\:\:\:\:\:\: \sin\theta = y$
Write an expression for $\cos\theta$ . What is $\cos\theta$ if $r = 1$ ?
Hint (c):
$\cos\theta = \frac{\text{adj}}{\text{hyp}}$