In a right triangle with legs 3 and 4, what is the length of the hypotenuse?

• A. 5
• B. 6
• C. 7
• D. 8

Answer: (A)

In a right triangle, the relationship between the sides is given by the Pythagorean theorem: the square of the hypotenuse equals the sum of the squares of the legs. With legs of 3 and 4, the hypotenuse is sqrt(3^2 + 4^2) = sqrt(9 + 16) = sqrt(25) = 5. This is the classic 3-4-5 triangle, where the hypotenuse must be 5. The other options don’t fit the equation for these leg lengths: their squares don’t add up to 25.