∫√(1-x^2)dx=x√(1-x^2)+∫x^2/√(1-x^2)dx=x√(1-x^2)+∫[(-√(1-x^2)+1/√(1-x^2)]dx
故∫√(1-x^2=【x√(1-x^2)+∫1/√(1-x^2)dx】/2=【x√(1-x^2)+acsinx】/2
∫√(1-x^2)dx=x√(1-x^2)+∫x^2/√(1-x^2)dx=x√(1-x^2)+∫[(-√(1-x^2)+1/√(1-x^2)]dx
故∫√(1-x^2=【x√(1-x^2)+∫1/√(1-x^2)dx】/2=【x√(1-x^2)+acsinx】/2