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bubblygum
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Proving trig identities
I have 2 more this time, thanks for the time!
[tex]-sin^2x-sin^2y+1=cos(x+y)cos(x-y)[/tex]
Compound, double, pythagorean, reciprocal, quaotient, etc.
R.H.S.
cos(x+y)cos(x-y)
= (cosxcosy-sinxsiny)(cosxcosy+sinxsiny)
= cos^2xcos^2y - sin^2xsin^2y
Not sure how to finish this off. Or have I started it off wrong?
sin(x+y)+sin(x-y)=2sinxcosx
Same as above
L.H.S.
sin(x+y)+sin(x-y)
= sinxcosy+sinycosx + sinxcosy-sinycosx
= sinxcosy+sinxcosy
= 2sinxcosy
I have 2 more this time, thanks for the time!
Homework Statement
[tex]-sin^2x-sin^2y+1=cos(x+y)cos(x-y)[/tex]
Homework Equations
Compound, double, pythagorean, reciprocal, quaotient, etc.
The Attempt at a Solution
R.H.S.
cos(x+y)cos(x-y)
= (cosxcosy-sinxsiny)(cosxcosy+sinxsiny)
= cos^2xcos^2y - sin^2xsin^2y
Not sure how to finish this off. Or have I started it off wrong?
Homework Statement
sin(x+y)+sin(x-y)=2sinxcosx
Homework Equations
Same as above
The Attempt at a Solution
L.H.S.
sin(x+y)+sin(x-y)
= sinxcosy+sinycosx + sinxcosy-sinycosx
= sinxcosy+sinxcosy
= 2sinxcosy
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