Trigonometric identities

[Guest]

how do you solve the following term into a single angle?
Ex. tan 42(deg)+ tan 38(deg) / 1- tan42(deg) * tan 38(deg).... the answer is tan 80(deg) but how do i solve for the answer????

 

[daon]

how do you solve the following term into a single angle?
Ex. tan 42(deg)+ tan 38(deg) / 1- tan42(deg) * tan 38(deg).... the answer is tan 80(deg) but how do i solve for the answer????

\(\displaystyle \L\\ \frac{tan42 + tan38}{1-tan42tan38}\)

This is the typical result of the identity \(\displaystyle \tan[a+b]\):

So, a = 42, b=38. 42+38 = 80.