Comments on: PRECALCULUS HELP!!!!!! PLZZ?

By: Fazaldin A

Fazaldin A — Tue, 19 Jan 2010 16:25:59 +0000

sin(x+60) – cos(x+30) = sinx
L.H.S. =
= sinx.cos60 + sin60.cosx – cosx.cos30 +sinx.sin30
= sinx/2 + sqrt(3).cosx/2 – cosxsqrt(3)/2 + sinx/2
= sinx = R.H.S.
References :

By: bryan

bryan — Tue, 19 Jan 2010 15:47:59 +0000

THIS IS THE BEST WEBSITE. I don’t think it has precalculus material, but everything from Calculus onwards. This Really helped me with the work. Lots of examples and information. Easy to follow.
References :
http://tutorial.math.lamar.edu/

Used this to help finish my minor in math.

By: sahsjing

sahsjing — Tue, 19 Jan 2010 15:23:59 +0000

sin(x+60) – cos(x+30)
= sinx cos60 + cosx sin60 – cosx cos30 + sinx sin30
= sinx cos60 + cosx sin60 – cosx sin60 + sinx cos60
= 2sinx cos60
= 2sinx (1/2)
= sinx
———
Attn: cos30 = sin60, and sin30 = cos60
References :