function calcHypotenuse(a, b) {
  return(Math.sqrt((a * a) + (b * b)));
}

console.log(calcHypotenuse(3, 4));
// expected output: 5

console.log(calcHypotenuse(5, 12));
// expected output: 13

console.log(calcHypotenuse(0, 0));
// expected output: 0

Math.sqrt(9); // 3
Math.sqrt(2); // 1.414213562373095

Math.sqrt(1);  // 1
Math.sqrt(0);  // 0
Math.sqrt(-1); // NaN
Math.sqrt(-0); // -0