Answer:
No. Se below for explanation
Step-by-step explanation:
If it is a right triangle it sides must meet the Pitgoras Theorem, wich says that the legs squared when summed must be equal to the square of the hypotenuse. Here the legs would be the sides of length 10 and 18, as the hypotenuse is always the longest. So we need to see:
10^ 2 + 18^2 = x
if x is equal to 21^2, so we can have a right triangle, if not, we cannot.
10^ 2 + 18^2 = 100 + 324
10^ 2 + 18^2 = 424
But:
21^2 = 441
So, as 10^2 + 18^2 < 21^2 this can not be a right triangle.
