Find the exact value of (tan pi/10 + tan pi/15) / (1- tan pi/10 tan pi/15)

Hey, I see you don't know your basic identities!

I'll do that last one for you:

\frac{tan \frac{\pi}{10} + tan \frac{\pi}{15}}{1- tan \frac{\pi}{10} tan \frac{\pi}{15}} = tan (\frac{\pi}{10}+\frac{\pi}{15})

iiOOOOOOOOO= tan(\frac{\pi}{6})


iiOOOOOOOOO= \frac{1}{\sqrt3} or \frac{\sqrt3}{3}