please help me.

Question

use trig. identities to find the exact value.

tan 25° + tan 5° / 1- tan 25° tan 5°

Answer 1

recall
tan(A+B) = (tanA + tanB)/(1 - tanAtanB)

I believe you meant to type
(tan 25° + tan 5°) /( 1- tan 25° tan 5°)

now it fits the above pattern and it equals

tan(25+5) = tan 30°

from my 30-60-90 triangle I know that
tan 30° = 1/√3 or √3/3