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Home > CCA2 > Chapter 12 > Lesson 12.2.1 > Problem 12-100


If and sin, find . Use what you know about the Pythagorean Identity and the unit circle to get started.

Remember that the Pythagorean Identity is .
Try substituting the given value of  into the equation, then solve for .

Take the square root of both sides to solve for .
Now use the unit circle to decide what the correct sign of the answer is.