来自彭旭昀的问题
sin(2π/3+α)=-cosα怎么证明的是3π/2搞错了
sin(2π/3+α)=-cosα怎么证明的
是3π/2搞错了
3回答
2020-02-01 18:35
sin(2π/3+α)=-cosα怎么证明的是3π/2搞错了
sin(2π/3+α)=-cosα怎么证明的
是3π/2搞错了
sin(3π/2+α)
=sin(π+π/2+α)
=-sin(π/2+α)
=-cosa
或者套用公式
sin(3π/2+α)=sin(3π/2)cosa+cos(3π/2)sina=-cosa
我知道了把后面的看成整体是吧
是的3π/2+α=π+(π/2+α)