Trig Identity

Homework Statement

Prove that tanx + 1 = secx.

Homework Equations

sinx/cosx + 1 = 1/cosx

NascentOxygen
Staff Emeritus

Homework Statement

Prove that tanx + 1 = secx.

Have you tried substituting a value, any value, to confirm this may be true?

It will be rather difficult to prove that it's an identity if it really isn't.

eumyang
Homework Helper

Homework Statement

Prove that tanx + 1 = secx.

Homework Equations

sinx/cosx + 1 = 1/cosx

The Attempt at a Solution

Check wherever you got this problem from to see if you copied it correctly. It looks like something is missing in the original problem.

Don't you mean tan2x + 1 = sec2x?

I wish I did. I am reviewing precalc with a student as a private tutorto prepare him for H.S. Calc. and this problem was one that neither of us could figure out.

I think you forgot the squares... if you meant them then
What people are telling you is that you cannot prove tan x+ 1= sec x, it is NOT true. For example if x= 45 degrees ($\pi/4$, the left side is 2 while the right side is $\sqrt{2}$.
You can prove that $tan^2 x+ 1= sec^2(x)$ for all x.