Posted by Don on Sunday, January 8, 2012 at 9:48pm.
The question is:
Set up a 2 column proof to show that each of the equations is an identity. Transform the left side to become the right side.
a. (tan + cot)^2 = sec^2 + csc^2
I'm having trouble with this.
b. (cos + sin)/cos + (cos  sin)/sin = csc sec
I'm having trouble with this too.

Trig  Reiny, Sunday, January 8, 2012 at 10:16pm
a)
you will need two identities here:
tan^2 x + 1 = sec^2 x , and
cot^2 x + 1 = csc^2 x
LS = tanx + cotx)^2
= tan^2x + 2tanxcotx + cot^2x
= sec^2x  1 + 2 + csc^2x , because (tanx)(cotx) = 1
= sec^2 x + csc^2 x
= RS
b) LS = (sinx(cosx + sinx) + cosx(cosx  sinx))/(sinxcosx)
= (sinxcosx + sin^2x + cos^2x  sinxcosx)/(sinxcosx)
= 1/sinxcosx
= (1/sinx)(1/cosx)
= cscx secx
= RS
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