Question

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

Answer 1

hi what grad our you in if its 6 grad i can help

Answer 2

Definitly not this is precalculus level trigonometry, sorry. Thanks for the offer though!:)

Answer 3

similarly sin (a+b)=sin a cos b+cos a sin b
sin (a-b)=sin a cos b-cos a sin b
add and find the answer.