- #1
KevinMWHM
- 27
- 0
prove
1-(cos(x)+sin(x))(cos(x)-sin(x))=2sin^2(x)
foil out the center
I get
1-cos^2(x)-cos(x)sin(x)+cos(x)sin(x)+sin^2(x)
the -cos(x)sin(x)+cos(x)sin(x) cancels to 0 leaving
1-cos^2(x)-sin^2(x)
then I'm lost...
I know I can switch 1-cos^2(x) to sin^2(x) but that doesn't help because I get
sin^2(x)-sin^2(x)=0
where am i going wrong?
1-(cos(x)+sin(x))(cos(x)-sin(x))=2sin^2(x)
foil out the center
I get
1-cos^2(x)-cos(x)sin(x)+cos(x)sin(x)+sin^2(x)
the -cos(x)sin(x)+cos(x)sin(x) cancels to 0 leaving
1-cos^2(x)-sin^2(x)
then I'm lost...
I know I can switch 1-cos^2(x) to sin^2(x) but that doesn't help because I get
sin^2(x)-sin^2(x)=0
where am i going wrong?