Thien D. answered 07/08/19
Duke MS Engineering Grad For Math Tutoring
The product identity states that:
sin(a)sin(b) = 0.5[cos(a-b) - cos(a+b)]
Using this identity, we can plug in "a" and "b":
2sin(52.5°)sin(97.5°) = 2*0.5[cos(52.5° - 97.5°) + cos(52.5° + 97.5°)]
= [cos(-45°) + cos(150°)]
= [cos(45°) - √(3)/2] , cosine is even
= [√(2)/2 - √(3)/2]
= [√(2) -√(3)]/4
I'm not sure what 2√ refers to, but I believe you will be able to solve the question from here