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Multiple Choice
Evaluate the integral: .
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Verified step by step guidance
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Step 1: Recognize that the integral involves the square of the cosine function, cos²(x). To simplify, use the trigonometric identity: cos²(x) = (1 + cos(2x)) / 2.
Step 2: Rewrite the integral using the identity: ∫₀^(π/2) 9 cos²(x) dx = ∫₀^(π/2) 9 * (1 + cos(2x)) / 2 dx.
Step 3: Factor out the constant 9/2 from the integral: (9/2) ∫₀^(π/2) (1 + cos(2x)) dx.
Step 4: Split the integral into two separate integrals: (9/2) [∫₀^(π/2) 1 dx + ∫₀^(π/2) cos(2x) dx].
Step 5: Evaluate each integral separately. For ∫₀^(π/2) 1 dx, calculate the area under the constant function 1 over the interval [0, π/2]. For ∫₀^(π/2) cos(2x) dx, use the substitution u = 2x, du = 2 dx, and adjust the limits of integration accordingly.