Answer: 20 cm
To solve this, use the Pythagorean Theorem, a² + b² = c², where a and b are the legs of the right triangle, and c is the hypotenuse of the right triangle.
**The Pythagorean Theorem only works for right triangles.**
Substitute in the values.
a² + b² = c²
12² + 16² = c²
Solve for c, the hypotenuse.
12² + 16² = c²
144 + 256 = c²
400 = c²
c = √400
c = 20