【1】f(x)=(1-sin2x)/(2cosx^2)f(x)=(1-sin2x)/(1+cos2x)1+cos2x≠0cos2x≠-12x≠π+2kπx≠π/2+kπ函数定义域:{x|x≠π/2+kπ}【2】tanA=-4/3tan2a=2tana/1-tana^2=24/7tan2a=sin2a/cos2a=24/7sin2a/cos2a=24/7sin...