3sin^2x+-2sin^2y=2sinx sin^2x+-sin^2y=?
问题描述：
3sin^2x+-2sin^2y=2sinx sin^2x+-sin^2y=?
答
3sin^2x±2sin^2y=2sinxsin^2x±sin^2y = (3sin^2x±2sin^2y-sin^2x)/2= (2sinx-sin^2x)/2= { 1 - (sinx-1)^2 }/2-1≤sinx≤1-2≤sinx-1≤00≤(sinx-1)^2≤4-4≤-(sinx-1)^2≤0-3≤ 1 - (sinx-1)^2 ≤ 1-3/2 ≤ {1 -...