Derive these identities using the addition or subtraction formulas for sine or cosine:

a. sin a sin b = 1 / 2 (cos (a - b) - cos (a + b))

b. sin a cos b = 1 / 2 (sin (a + b) + sin (a - b))

Question

Mathematics

Conley

3 May, 05:29

Derive these identities using the addition or subtraction formulas for sine or cosine:

a. sin a sin b = 1 / 2 (cos (a - b) - cos (a + b))

b. sin a cos b = 1 / 2 (sin (a + b) + sin (a - b))

+4

Answers (1)

Know the Answer?

Barbara Oconnor · Answer 1

Step-by-step explanation:

cos (a-b) - cos (a+b) = 2 (sina x sinb)

using formulae of cos (a-b) & cos (a+b)

cos a cos b + sina sinb - cosa cosb + sina sinb=2 sina sinb

2 sina sinb = 2 sina sinb

proved!

Derive these identities using the addition or subtraction formulas for sine or cosine:a. sin a sin b = 1 / 2 (cos (a - b) - cos (a + b))b. sin a cos b = 1 / 2 (sin (a + b) + sin (a - b))

Derive these identities using the addition or subtraction formulas for sine or cosine:

a. sin a sin b = 1 / 2 (cos (a - b) - cos (a + b))

b. sin a cos b = 1 / 2 (sin (a + b) + sin (a - b))