In a right triangle, the legs measure 3 and 4. What is the length of the hypotenuse?

• A. 6
• B. 5
• C. 4
• D. 7

Answer: (B)

In a right triangle, the longest side is the hypotenuse, and its length follows the Pythagorean theorem: the sum of the squares of the legs equals the square of the hypotenuse. With legs 3 and 4, the hypotenuse squared is 3^2 + 4^2 = 9 + 16 = 25, so the hypotenuse is the square root of 25, which is 5. This is the classic 3-4-5 triangle, so 5 is longer than both legs, fitting as the hypotenuse. The other options don’t satisfy the equation since their squares don’t add up to 25.