问题描述:
∫(0,3π)根号下1-cosxdx=
问题描述:
∫(0,3π)根号下1-cosxdx=
=根号2·∫(0,3π)根号下[(1-cosx)/2]dx =根号2·∫(0,3π)根号下[sin^2(x/2)]dx =根号2·∫(0,3π)|sin(x/2)|dx =2根号2·[∫(0,2π)sin(x/2)d(x/2)-∫(2π,3π)sin(x/2)d(x/2)] =2√2·[-cos(x/2)|(0,2π)+cos(x/2)dx|(2π,3π)] =2√2×(2-1) =2√2