Which statement about a right triangle is true? a. the length of each leg equals 1212 of the hypotenuse. b. the square of the hypotenuse is equal to the sum of the squares of the legs. c. one leg is always longer than the hypotenuse. d. a right triangle can have only one obtuse angle.

The correct answer is:  [B]:

   "The square of the hypotenuse is equal to the sum of the squares of the legs."

Note:  Hence the formula / equation for the Pythagorean theorem for a right triangle:

        a² + b² = c²  ;  

in which "c" is the length of the hypotenuse of a right triangle; 
& in which "a" and  "b" are the lengths of the other two sides of the right triangle.