求证cos(3π/2+α)=sinα

问题描述:

求证cos(3π/2+α)=sinα

cos(3π/2+α)=cos[π+(a+π/2)]=-cos(a+π/2)=sina
所以得证
根据诱导公式能不能详细点有过程当中的就是过程啊!!cos(π+a)=-cos a把(α+π/2)看做整体cos(a+π/2)=-sina或者展开cos(3π/2+a)=cos(3π/2)cosa-sin(3π/2)sina又因为cos(3π/2)=0sin(3π/2)=-1所以cos(3π/2+a)=sina