could you help me on the following,

rcosxcosy * rsinxcosy

-rsinxsiny * sinxsiny

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- Feb 17th 2008, 01:57 PMheroicmultiplying trig functions
could you help me on the following,

rcosxcosy * rsinxcosy

-rsinxsiny * sinxsiny - Feb 17th 2008, 04:19 PMTwistedOne151

-Kevin C. - Feb 18th 2008, 02:08 AMheroic
cheers mate.

now could you possibly help me simplify the following plz,

cosx[(r^2sinxcos^2y) - (r^2sinxcosxsin^2y)]

(-rsinx)[(rsin^2xcos^2y) - (-rsin^2xsin^2y)]

I'm sorry i'm askin for help, i kno this must be easy, but i can't do it. lol - Feb 18th 2008, 02:31 AMPeritus
try using the following identities:

you might also take a look at this:

Table of Trigonometric Identities