Yes, they can and here is why! The Pythagorean Theorum tells us that there is a relationship between the 2 sides and the hypotenuse (the side directly across from the right angle) of a right triangle. The formula a^2 + b^2 = c^2. ^ means squared. So, 18 squared (18 x 18 = 324) + (24 x 24 = 576) = 900. 30 x 30 = 900, so it is possible for these to be the side lengths. This would be a right scalene triangle.
