先求(sinα)^6+(cosα)^6 的值(sinα)^6+(cosα)^6=[(sinα)^2+(cosα)^2][(sinα)^4-(sinα)^2(cosα)^2+(cosα)^4]=1[(sin²α+cos²α)²-3sin²αcos²α]=1-3/4(4sinαcosα)²=1-3/4(...