Question

求定积分详细步骤

Answer 1

∫(π/3->π) sin(x+π/3) dx
=∫(π/3->π) sin(x+π/3) d(x+π/3)
= -[ cos(x+π/3) ]|(π/3->π)
=- [ cos(π+π/3) -cos(π/3+π/3) ]
=- [ cos(4π/3) -cos(2π/3) ]
=-( -1/2 +1/2 )
=0

追问

cos 2/3π为什么等于-1/2

追答

cos(2/3π)
=-cos(π/3)
=-1/2

追问

看不懂

追答

cos(2/3π)
=-cos(π-(2/3)π)
=-cos(π/3)
=-1/2

追问

不懂