Find the exact value of the expression.cos⁡80°cos⁡20°+sin⁡80°sin⁡20°\cos80\degree\cos20\degree+\sin80\degree\sin20\degreecos80°cos20°+sin80°sin20°

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1. Measuring Angles39m
2. Trigonometric Functions on Right Triangles2h 5m
3. Unit Circle1h 19m
4. Graphing Trigonometric Functions1h 19m
5. Inverse Trigonometric Functions and Basic Trigonometric Equations1h 41m
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6. Trigonometric Identities and More Equations

Sum and Difference Identities

Trigonometry6. Trigonometric Identities and More EquationsSum and Difference Identities

Multiple Choice

Find the exact value of the expression.
$\cos80\degree\cos20\degree+\sin80\degree\sin20\degree$

$-\frac12$

$\frac12$

$\frac{\sqrt3}{2}$

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Find the exact value of the expression.
$\cos80\degree\cos20\degree+\sin80\degree\sin20\degree$

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Find the exact value of the expression.﻿cos⁡80°cos⁡20°+sin⁡80°sin⁡20°\cos80\degree\cos20\degree+\sin80\degree\sin20\degreecos80°cos20°+sin80°sin20°﻿

Find the exact value of the expression.
$\cos80\degree\cos20\degree+\sin80\degree\sin20\degree$