Question

express the following products into sum or difference form: sin40sin50​

Answer 1

ANSWER

Sum-to-Product and Product-to-Sum Formulas

Sum-to-Product and Product-to-Sum FormulasExpressing Products as Sums

We have already learned a number of formulas useful for expanding or simplifying trigonometric expressions, but sometimes we may need to express the product of cosine and sine as a sum.

We can use the product-to-sum formulas, which express products of trigonometric functions as sums. Let’s investigate the cosine identity first and then the sine identity.

Expressing Products as Sums for Cosine

We can derive the product-to-sum formula from the sum and difference identities for cosine.

ANSWER By ARYAN (◕ᴗ◕✿)