Posted by **Corin** on Friday, May 4, 2007 at 12:26am.

How do you verify:

1.) sinxcosx+sinx^3secx=tanx

2.) (secx+tanx)/(secx-tan)=(secx+tanx)^2

I tried starting from the left on both problems, but am stuck.

like I said before, change everything into sines and cosines.

for the first one:

LS= sinxcosx + (sin^3x)cosx

=(sinxcos^2x + sin^3x)/cosx

=

=

factor out the sinx, and look what you have left inside the bracket!

two more steps!

the second one is just as easy.

LS = (1/cosx + sinx/cosx)(1/cosx - sinx/cosx)

=

=

can you see the common factor, and the difference of squares pattern?

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