行列式第四题按定义怎么算要过程谢谢 20
2017-10-11
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(cosθ)^4=[(1-cos(2θ)]^2/4
=1/4+cos²2θ/4-1/2cos(2θ)
=1/4+[1-cos(4θ)]/8-1/2cos(2θ)
=3/8-cos(4θ)/8-1/2cos(2θ).
8∫(cosθ)^4dθ=8[3/8θ-sin(4θ)/32-1/4sin(2θ)]=3θ-sin(4θ)/4-2sin(2θ),所以定积分的值为3π2.
=1/4+cos²2θ/4-1/2cos(2θ)
=1/4+[1-cos(4θ)]/8-1/2cos(2θ)
=3/8-cos(4θ)/8-1/2cos(2θ).
8∫(cosθ)^4dθ=8[3/8θ-sin(4θ)/32-1/4sin(2θ)]=3θ-sin(4θ)/4-2sin(2θ),所以定积分的值为3π2.
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