2017高考数学b

① 2017-2018高等数学B答案

令x=asinθ，dx=d(asinθ)=acosθdθ
原式=∫[(asinθ)²/acosθ]acosθdθ
=∫(asinθ)²dθ
=a²∫sin²θdθ
=a²∫[(1-cos2θ)/2]dθ
=(a²/2)∫(1-cos2θ)dθ
=(a²/2)[θ-(1/2)sin2θ]+C
=(a²/2)[arcsin(x/a)-(x/a)·√(x²-a²)/a]+C
=(a²/2)arcsin(x/a)-[x√(x²-a²)/2]+C