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# C3 trig identities watch

1. ( sin(theta) + cos(theta) )( 1- sin(theta)cos(theta) ) = sin^3(theta) + cos^3(theta)

LHS= sin(theta) - sin^2(theta)cos(theta) + cos(theta) - sin(theta)cos^2(theta)

don't know where to go from there?
2. Chage the sin^2xcosx and cos^2xsinx so that they each only have one of cos or sin in
3. (Original post by AndyOC)
( sin(theta) + cos(theta) )( 1- sin(theta)cos(theta) ) = sin^3(theta) + cos^3(theta)

LHS= sin(theta) - sin^2(theta)cos(theta) + cos(theta) - sin(theta)cos^2(theta)

don't know where to go from there?
sub in (1 - cos^2(theta)) for sin^2(theta)

sub in (1 -sin^2(theta)) for cos^2(theta)

and it should all simplify nicely

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Updated: October 26, 2015
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