Show that:
Using sin 3A = 3 sinA - 4 sin3A
cos 3A = 4 cos3A - 3 cos A
We have, L.H.S. =
=
=
=
= 6 - 4(1) = 6 - 4 = 2 = R.H.S.
∴ L.H.S. = R.H.S.
Hence,