和差化积公式
sum-to-product identities Identities that express sums or differences of trigonometric functions as products, e.g., $\sin A + \sin B = 2 \sin\frac{A+B}{2} \cos\
CSCA 数学 考试术语
sum-to-product identities Identities that express sums or differences of trigonometric functions as products, e.g., $\sin A + \sin B = 2 \sin\frac{A+B}{2} \cos\
CSCA 数学 考试术语