Kevin C. answered 04/24/16
Tutor
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Successful Math Tutor -- Recently retired high school math teacher
Hi, Leah.
Remember that 1-sin2x = cos2x
So if you multiply this fraction (cosx)/(1-sinx) by (1+sinx)/(1+sinx) you will get:
(cosx)(1+sinx)/(1-sin2x) = (cosx)(1+sinx)/(cos2x) or (1+sinx)/(cosx)
or: 1/cosx + sinx/cosx = secx + tanx.
I hope this helps.
Kevin