On Jan 20, 7:22 pm, Angus Rodgers <twir...@bigfoot.com> wrote: > On Tue, 20 Jan 2009 08:19:58 +0000, I groggily wrote: > >[...] So, the identity you have to prove is > >equivalent to the one you have just written out - which follows > >simply from the given algebraic identity [...] > > ... in conjunction, of course, with the known trigonometric > identity: > > cos(x)^2 + sin(x)^2 = 1 > > -- > Angus Rodgers
Are you implying that (1+sinx)(1-sinx) = 1 - (sinx)^2 = 1 - (sin^2)x = 1 - sin(x)^2 ?
My booklet writes square relations (sin^2)x, you seem to write sin(x) ^2 and I've always thought that sinx * sinx = (sinx)^2 which was not equal to (sin^2)x. Which means I MUST have been wrong because = 1 - (sinx)^2 WOULD result in no further steps possible. But as I've clearly seen, it gets re-arranged (with some correct stuff on the left hand side of the equals sign) to be one of the trigonometric identities and therefore my original problem is proven!... :|