View Full Version : Proofs? Identities?
mathretard4592222
Oct 22, 2007, 07:03 PM
Some one teach me precal I can't do any of this.
Prove the identity:
(cosx)(tanx+sinxcotx)=sinx+cos^2x (thats cos squared times x)
s_cianci
Oct 22, 2007, 07:05 PM
Change everything to sin and cos. Recall that tan = sin/cos , cot = cos/sin , sec = 1/cos and csc = 1/sin. Take the left side of the equation, (cosx)(tanx+sinxcotx), do the algebra and it'll fall right into place.
Kirandeep Singh
Oct 24, 2007, 07:13 AM
(cosx)(tanx + sinxcotx) = sinx + cos^2 x
Taking left hand side and putting tanx = sinx/cosx and cotx = cosx/sinx
cosx(sinx/cosx + sinx*cosx/sinx)
= sinx + cos^2x
Hence proved
nycfunction
Nov 11, 2007, 12:05 PM
Some one teach me precal I can't do any of this.
Prove the identity:
(cosx)(tanx+sinxcotx)=sinx+cos^2x (thats cos squared times x)
tanx = sinx/cosx
cotx = cosx/sinx
On the left side:
(cosx)(tanx+sinxcotx)= cosx(sinx/cosx + sinx(cosx/sinx)
cosx(sinx/cosx) = sinx... cosx cancels out.
sinx(cosx/sinx) = cosx(cosx) = cos^2x
Final answer: sinx + cos^2(x) = right side
terryg752
Nov 11, 2007, 03:49 PM
(cosx)(tanx+sinxcotx)=sinx+cos^2x
Left hand side =
cosx(sinx/cosx + sinx cosx /sinx)
= sinx + cos^2 x
= right hand side