This math topic focuses on using the Pythagorean theorem to solve for missing sides in right-angled triangles. It involves identifying the correct approach: either adding the squares of the two shorter sides to find the hypotenuse, or subtracting the square of one side from the square of the hypotenuse to find a shorter side. The problems provide scenarios with different side arrangements and ask to select the appropriate calculation method. It includes images of triangles with sides labelled, aiding in visual understanding. This set is a Level 1 introduction to basic Pythagorean theorem applications.