What is the exact value of cos(2 theta) if sin(theta) = 3/5?
Answer and explanation
Correct answer: C. 7/25
Using the double-angle formula cos(2 theta) = 1 - 2 sin^2(theta): cos(2 theta) = 1 - 2 (3/5)^2 = 1 - 2 * (9/25) = 1 - 18/25 = 7/25.
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