CPM Homework Help : PCT Problem 11-75

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Home > PCT > Chapter Ch11 > Lesson 11.2.1 > Problem 11-75

11-75.

Simplify the following into a single trigonometric term.

$\cos a \cos b -\sin a \sin b$
Hint (a):
Review the angle sum identity for cosine.

$20 \sin(3x)\cos(3x)$
Hint (b):
Review the double-angle identity for sine.

$\sin(3x)\cos(x)-\cos(3x)\sin(x)$
Hint (c):
Review the angle difference identity for sine.

$\sin^2(4y)-\cos^2(4y)$
Hint (d):
This expression can be rewritten as $−(\cos^2(4y) − \sin^2(4y))$ .

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