Question

Prove that : sin a – 2 sin3 a 2 cos3 a – cos a = tan



a.

Answer 1

Answer:

(sinA - 2sin^3A)/ (2cos^3A - cosA)

sin (1 - 2sin^2) / cos (2cos^2 - 1)

sin {1 - 2 (1 - cos^2) } / cos (2cos^2 - 1) (sin2 = 1 - cos2)

sin (1 - 2+2cos^2) / cos (2cos^2 - 1)

sin (2cos^2 - 1) / cos (2cos^2 - 1)

sin/ cos {(2cos^2 - 1) / (2cos^2 - 1) } cancel each other

tan