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August 28, 2014

August 28, 2014

Posted by **ann** on Friday, April 30, 2010 at 10:07pm.

use trig. identities to find the exact value.

tan 25° + tan 5° / 1- tan 25° tan 5°

- trig -
**Reiny**, Friday, April 30, 2010 at 11:06pmrecall

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

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