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Algebra 2

Course: Algebra 2 > Unit 11

Lesson 3: The Pythagorean identity
Math
Algebra 2
Trigonometry
The Pythagorean identity
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Use the Pythagorean identity

CCSS.Math: HSF.TF.C.8, HSF.TF.C
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Problem

The angle theta, start subscript, 1, end subscript is located in Quadrant start text, I, V, end text, and sine, left parenthesis, theta, start subscript, 1, end subscript, right parenthesis, equals, minus, start fraction, 13, divided by, 85, end fraction .
What is the value of cosine, left parenthesis, theta, start subscript, 1, end subscript, right parenthesis?
Express your answer exactly.
cosine, left parenthesis, theta, start subscript, 1, end subscript, right parenthesis, equals
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