Question

Prove that sin7a -sina/sin8a-sin2a =cos4a sec5a

Answer 1

we know that sinA - sinB = 2 cos(A+B)/2 sin(A-B)/2
so sin7a-sina/sin8a-sin2a
= 2cos4a.sin3a/2cos5a.sin3a
=cos4a/cos5a
=cos4a.sec5a

Answer 2

Answer:

Step-by-step explanation:

Dear Student

Use identity sinC−sinD=2cos(C+D / 2)sin(C−D / 2)