If legs of a right triangle are 3 and 4, the hypotenuse is

1. Use a^2 + b^2 = c^2 with a = 3, b = 4. 2. c^2 = 9 + 16 = 25. 3. c = sqrt(25) = 5. 4. So the hypotenuse is 5. _Source: Selina Concise Mathematics Class 9, Ch on Pythagoras Theorem (Mistral OCR'd PDF), section on numerical example_