The sum of 1/6, 2/3, and 1/4 is

1/6+2/3+1/4 
First find the highest common multiple of the denominators=12
Then multiply each term by the quotient of 12/denominator
So...it becomes 2/12+8/12+3/12
Add all the numerators and keep the denominator constant
It becomes (2+8+3)/12=13/12
                                 =1 1/12

Its a right angled triangle not a right triangle