Please prove this...

 see proof below

Step-by-step explanation:

Use the following Sum to Product Identities:

sin (A) - sin (B) = 2 cos (A+B)/2 · sin (A-B)/2

sin (A) + sin (B) = 2 sin (A+B)/2 · cos (A-B)/2

Given:  sin Ф = k sin β      -->   (sin Ф)/(sin β) = k

Proof RHS → LHS

1.677

step-by-step explanation:

i'm not good at explaining stuff but if you need an answer i'm here for you.

this may not be at all, but i use the same website you're using for school, and if i'm stuck doing one of these i try to look for it on the section.