cos83°·cos23°+sin83°·sin23°=
问题描述：
cos83°·cos23°+sin83°·sin23°=
答
原式=1/2
∵由公式：cos(α-β) = cosαcosβ + sinαsinβ
∴cos83°·cos23°+sin83°·sin23° = cos(83° - 23°) = cos60° = 1/2