Question

prove that
(sin A + sin 3A)/(cos A + cos 3A) = tan 2A

Answer 1

Answer:

SOLVED BELOW

Step-by-step explanation:

sin A + sin 3A / cosA + cos3A = 2sin2Acos( -A ) / 2cos2Acos(-A) = 2sin2Acos( A ) / 2cos2Acos(A) ( as cos (-theta) = cos theta

then cosA and 2 get cancelled and we get sin2A / cos2A = tan 2A

HOPE YOU UNDERSTAND