化简(sinα)^2*(sinβ)^2+(cosα)^2(cosβ)^2-1/2cos2αcos2β

问题描述:

化简(sinα)^2*(sinβ)^2+(cosα)^2(cosβ)^2-1/2cos2αcos2β

cos2αcos2β=(cos²α-sin²α)(cos²β-sin²β)=cos²αcos²β-cos²αsin²α-sin²αcos²β+sin²αsin²α所以原式=(2cos²αcos²β+2sin²...