Question

find the perimeter of a 30 30 90 triangle with the hypotenuse of 18

Answer 1

do you mean 30-60-90 triangle?

if so, the rules are:
1) short leg is 1/ 2 of the hypotenuse
2) long leg is sqr(3) * short leg

and perimeter is the sum of the lengths of all 3 sides.