∫(4-x^2)^1/2dx怎么解

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∫(4-x^2)^1/2dx怎么解

∫(4-x^2)^1/2dx怎么解
∫(4-x^2)^1/2dx怎么解

∫(4-x^2)^1/2dx怎么解
∫(4-x^2)^1/2dx
let
x= 2sina
dx = 2cosa da
∫(4-x^2)^1/2dx
=∫2cosa (2cosada)
= ∫ 2(cos2a+1) da
= sin2a + 2a + C
=(1/2) x(4-x^2)^1/2 + 2arcsin(x/2) +C

x=2sina
dx=2cosada
原式=∫cosa*2cosada
=(1+cos2a)da
=a+1/2*sin2a++C
=a+sinacosa+C
=arcsin(x/2)+x/2*√(1-x²/4)+C