Question

prove that; 4cos^3 20+sin^3 10=3(cos 20+sin10)

Answer 1

Answer:

Here is the soln in the attached file

Hope it helps ❤️ ❤️ ❤️

Answer 2

Answer:

4(cos^3 10+sin^3 20)

=4cos^3 10+4sin^320

=cos30+3cos10+3sin20-sin60

=3cos10+3sin20

=3(cos10+sin20)

(prove)