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pandalover123
Jul 30, 2009, 06:12 AM
how do you verify using identities

(tanx+cotx)/cosx = secx

ebaines
Jul 30, 2009, 08:32 AM
how do you verify using identities

(tanx+cotx)/cosx = secx

You have an error in your identity formula - please check it. Perhaps you mean this:

(tanx + cotx)*sinx = secx

Or maybe: (tanx + cotx)*cosx = cscx?

Best way to approach these types of problems is to replace the tanx, cot, secx terms with the eqiuvalent sinx and cosx terms, then simplify. You'll find that you can then use basic identities like sin^2x + cos^2x = 1 to get it to work out.

kapilagayan
Jul 30, 2009, 09:10 AM
You have an error in your identity formula - plase checkit. Perhaps you mean this:

(tanx + cotx)*sinx = secx

Or maybe: (tanx + cotx)*cosx = cscx ??

Best way to approach these types of problems is to replace the tanx, cot, secx terms with the eqiuvalent sinx and cosx terms, then simplify. You'll find that you can then use basic identities like sin^2x + cos^2x = 1 to get it to work out.

:):)

cnd822
Jan 22, 2011, 07:43 PM
First you have to choose a side. I would choose the left because it's the most complicated. Substitute tangent for sine/cosine, and substitute cotangent for cosine/sine. So now you have (Sine/cosine) + (cosine/sine)all over cosine. You need to add the numerator together. To do this you need a LCD, which is sine multiplied by cosine. The new numerator is sine^2x + cos^2x. Substitute the numerator for one because that is what sine^2x + cos^2x is equivalent to. Then put that over the denominator of cosine. 1/cosine is the same thing as secant. It's the reciprocal relation. So they are equal.