1、正切函数y=tanx在x=π/4处切线方程dy/dx = sec²x当x=π/4,y = 1dy/dx = 2切线方程：y = 2x + C1 = 2×¼π + C,C = 1 - ½π答案：y = 2x + 1 - ½π2 、y =（sin x)×(1+cos x)y = sin x...