三角换元公式：根式形式 √a2-x2用x=asint（-π/2<=t<=π/2）替换，√a2+x2用x=atant（-π/2<=t<=π/2）替换，√x2-a2用x=asect（t不等于π/2）替换。
匿名回答于2020-10-18 13:05:26
