Mathematics for IGCSE & O level - Pythagoras' Theorem And Trigonometry (Section 5 - No. 18)
If you know the lengths of two sides of a right triangle, how can you find the length of the third side?
Use the Law of Sines
Use the Law of Cosines
Use the Pythagorean Theorem
Use trigonometry
Explication
The Pythagorean Theorem is used to find the third side length.