Posted by **anonymous** on Sunday, April 14, 2013 at 3:27pm.

For each of the following determine whether or not it is an identity and prove your result.

a. cos(x)sec(x)-sin^2(x)=cos^2(x)

b. tan(x+(pi/4))= (tan(x)+1)/(1-tan(x))

c. (cos(x+y))/(cos(x-y))= (1-tan(x)tan(y))/(1+tan(x)tan(y))

d. (tan(x)+sin(x))/(1+cos(x))=tan(x)

e. (sin(x-y))/(sin(x)cos(y))=1-cot(x)tan(y)

f. sin(x)sin(y)=(1/2)[cos(x-y)-cos(x+y)]

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