Mathematics for IGCSE & O level - Pythagoras' Theorem And Trigonometry (Section 6 - No. 42)
What information is necessary to find the missing lengths of a right triangle using the Pythagorean Theorem?
The lengths of two sides
The measure of one angle.
The ratio of two sides.
The area of the triangle.
Explication
Knowing the lengths of two sides, you can use the theorem to find the missing side.