In every triangle, length of two sides must be greater (not equal or lesser) than the length of third side of the triangle...so it is not possible to have triangle of side lengths 9 9 and 20. Apologies if i m wrong.
The sides are either 9 9 20 or 20 20 9. The sum of any two sides must be greater than any one side in a triangle, so the sides cannot be 9 9 20 and are therefore 20 20 9. The perimeter is the length of all sides, which is 49.
