化简cos^2 a(2cos^2+3)-sin^2 a(2cos^2+3)-4sin^2 acos^2 a+3

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化简cos^2a(2cos^2+3)-sin^2a(2cos^2+3)-4sin^2acos^2a+3化简cos^2a(2cos^2+3)-sin^2a(2cos^2+3)-4sin^2acos^2a

化简cos^2 a(2cos^2+3)-sin^2 a(2cos^2+3)-4sin^2 acos^2 a+3
化简cos^2 a(2cos^2+3)-sin^2 a(2cos^2+3)-4sin^2 acos^2 a+3

化简cos^2 a(2cos^2+3)-sin^2 a(2cos^2+3)-4sin^2 acos^2 a+3
原式=cos²a(2-2sin²a+3)-2sin²acos²a-3sin²a-4sin²acos²a+3
=5cos²a-2sin²acos²a-2sin²acos²a-3sin²a-4sin²acos²a+3
=5cos²a-3(1-cos²a)+3
=8cos²a