Pythagoras theorem: In a right triangle, if the hypotenuse, perpendicular, and base are its sides, then as per the theorem, the square of the hypotenuse side is equal to the sum of the square of the base and the square of the perpendicular. Hence, if we know any two sides, then we can easily find the third side of the triangle.
C. 20 ft, 20 ft, 50 ft correct?