Answer:
We can use the Pythagorean theorem to determine if the triangle is a right triangle. The Pythagorean theorem states that in a right triangle, the square of the length of the hypotenuse (the longest side) is equal to the sum of the squares of the lengths of the other two sides.
Let's label the sides of the triangle as a = 18 mm, b = 25 mm, and c = 15 mm. We want to see if a right angle exists between sides a and b, so we will check if c² = a² + b².
a² + b² = 18² + 25² = 324 + 625 = 949
c² = 15² = 225
Since c² is not equal to a² + b², the triangle is not a right triangle.
Therefore, the answer is no, the triangle is not a right triangle.