Question 181073
THINGS YOU SHOULD KNOW:
tan60= sin60/cos60 = (sqr(3)/2)/(1/2)= sqr(3)
tan30= sin30/cos30 = (1/2)/(sqr(3)/2)= 1/sqr(3)= sqr(3)/3

(tan60-tan30)/(1+tan60tan30)
(sqr(3)-sqr(3)/3)/(1+sqr(3)*1/sqr(3))
(3sqr(3)/3 - sqr(3)/3)/ (1+1)
(2sqr(3)/3)/ (2)
(2sqr(3)/3)(1/2)
sqr(3)/3

and sqr(3)/3=tan30