Answer:
2√41
Step-by-step explanation:
If the third side is x, we can use the Pythagorean Theorem (a² + b² = c² where a and b are legs and c is the hypotenuse - a and b would be 12 and √20 and c would be x) to write the following equation:
12² + (√20)² = x²
144 + 20 = x²
164 = x²
√164 = √x²
x = ±√164 = ±2√41
x = -2√41 is an extraneous solution because x cannot be negative, therefore, the answer is x = 2√41.
