求下列各式的值 已知cos(a-π/3)=12/13,π/3小于a小于π/2,求cosa

问题描述:

求下列各式的值 已知cos(a-π/3)=12/13,π/3小于a小于π/2,求cosa

因为cos(a-π/3)=12/13,π/3