#### Answer

Fill the blanks with:
right
hypotenuse
legs

#### Work Step by Step

See the paragraph before the Pythagorean Theorem. The angle $90^{\circ}$ is called a right angle.
A triangle with one angle measuring $90^{\circ}$ is called a right triangle.
The side opposite the $90^{\circ}$ angle is called the hypotenuse. The other sides are called legs.