as88650m 寫到:1. 2cos220•sec220+cot215-csc215有值等於....?
2.化簡3(1-tan4θ)•cos2θ+3sin2θ•sec2θ=.....
最近剛學到三角函數
還不是很會
希望大家幫忙
2.化簡3(1-tan4θ)•cos2θ+3sin2θ•sec2θ=.....
3(1-tan4θ)•cos2θ+3sin2θ•sec2θ
=3(1+tan2θ)(1-tan2θ)•cos2θ+3sin2θ•(1/cos2θ)
=3(sec2θ)(1-tan2θ)•cos2θ+3tan2θ
=3(1/cos2θ)(1-tan2θ)•cos2θ+3tan2θ
=3(1-tan2θ)+3tan2θ
=3