# Math Trig Identities?

by Stanc
Tags: identities, math, trig
 P: 60 Hi im in need of some help for this question: 1+tanx/1-tanx = tan(x+(∏/4)) It is easy to solve with the tan trig identites on the right side however, my teacher had told me to do it with SIN and COS only. Im not sure if its possible and was looking for some insight Left Side: Cosx+Sinx/Cosx-Sinx Right Side: End up with {(SinxCos∏/4) + (CosxSin∏/4)}/ (CosxCos∏/4) - (SinxSin∏/4) Can anyone give me some insight?
 HW Helper P: 774 A good first step is to replace cos($\pi$/4) and sin($\pi$/4) by their actual values.
P: 60
 Quote by pasmith A good first step is to replace cos($\pi$/4) and sin($\pi$/4) by their actual values.
Yes. I have tried that but then i get stuck at:

(Sinx(√2/2)) + (Cosx(√2/2)) / (Cosx(√2/2)) - (Sinx(√2/2))

IS there anything i can do?

Engineering
HW Helper
Thanks
P: 6,352

## Math Trig Identities?

Don't get confused by all the notation. This is just the same as simplfying something like
$$\frac{3a + 3b}{3c - 3d}$$
P: 60
 Quote by AlephZero Don't get confused by all the notation. This is just the same as simplfying something like $$\frac{3a + 3b}{3c - 3d}$$
I dont think im catching it. I understand how to simplify the example you had but i cannot factor out a sin or a cos?
 P: 60 Nevermind, I feel reallydumb... i got it, thanks guys
Mentor
P: 21,026
 Quote by Stanc Hi im in need of some help for this question: 1+tanx/1-tanx = tan(x+(∏/4))
The left side needs parentheses!

What you wrote is 1 + (tanx)/1 - tanx, which is equal to 1.

What you meant was (1 + tanx)/(1 - tanx).

 Related Discussions Precalculus Mathematics Homework 24 Precalculus Mathematics Homework 5 Precalculus Mathematics Homework 5 Precalculus Mathematics Homework 3 General Math 3