1.
This can be rewritten as:
Recall that
2.
Pull one factor of each sine and cosine out:
Can you do it now?
Prove that
tan A - (sec A sin^3A / 1 + cos A ) = sin A
Obtained from my Workings
(sin A / cos A) - (sin^3A / cos A + cos^2 A )(From here on I don't know what to do aside from subtracting it)
Prove that
sin^3 A / cos A - cos^3A = tan A
Obtained from my Workings: Can't think of Any
Thanks, hoping for a fast reply
Arnold,