Question

Please help me please

Answer 1

Answer:

they are identical. proved below.

Step-by-step explanation:

• formula:  $sin(t)+sin(s) = 2sin(\frac{t+s}{2} )cos(\frac{t-s}{2} )$

using the formula to proof:

$sin9a+sin5a$

$2sin(\frac{9+5}{2})* cos(\frac{9-5}{2})$

$2sin7a * cos2a$

True. proved that they are identical.