Find the perimeter of a right-angled triangle if its legs are 9 cm and 40 cm.

1) In order to find the hypotenuse of a right triangle, we use the Pythagorean theorem, which says that the square of the hypotenuse is equal to the sum of the squares of the legs of this triangle.

Let’s denote the value of the hypotenuse – x, then x ^ 2 = 9 ^ 2 + 40 ^ 2 = 1681.

Taking the square root of 1681, we get √1681 = 41 (cm).

2) Knowing all sides of the triangle, we find the perimeter as the sum of all sides of the triangle:

41 + 9 + 40 = 90 (cm).

Answer: The perimeter of a right-angled triangle is 90 centimeters.