Exercise 1 Page 540

To find the missing side of the triangle, we will use the Pythagorean Theorem. a^2+b^2=c^2In the formula, a and b are the legs and c is the hypotenuse of a right triangle. We are given a triangle with a=12, b=9, and c=x.

Let's substitute these values into the formula.

Since a negative side length does not make sense, we only need to consider positive solutions. Therefore, x=15. We can see that 12, 9, and 15 are all integers and satisfy a^2+b^2=c^2. Therefore, the side lengths form a Pythagorean Triple.