Question

Simplify: (sin2a)/sina = (cos2a)/cosa

Answer 1

2sin(a)cos(a)/sin(a) = cos(2a)/cos(a)
2cos(a) = cos(2a)/cos(a)
\[2\cos^2(a) = \cos(2a)\]
\[2\cos^2(a) = \cos^2(a) - \sin^2(a)\]
\[\cos^2(a) = -\sin^2(a)\]
1 = 0
No solution!

Answer 2

I get now! I think I'm over thinking the question. Thank you!