\(\int \limits_{ - \frac{\pi }{2}}^{\frac{\pi }{2}} \left( {\frac{{\sin 2x\sin x}}{2} + {{\cos }^3}x} \right)dx\) bằng
A. 2
B. \(2\pi \)
C.
\(\pi \)D.
Đáp án: A
Vì \(\frac{{\sin 2x\sin x}}{2} + {\cos ^3}x = ({\sin ^2}x + {\cos ^2}x)\cos x = \cos x\) nên
\(\int \limits_{ - \frac{\pi }{2}}^{\frac{\pi }{2}} \left( {\frac{{\sin 2x\sin x}}{2} + {{\cos }^3}x} \right)dx = \int \limits_{ - \frac{\pi }{2}}^{\frac{\pi }{2}} \cos xdx = 2\)
-- Mod Toán 12
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