Hi!
A <u>hypotenuse</u> is the longest leg in a right triangle.
A <u>right triangle</u> is a triangle that has one 90 degree angle.
The hypotenuse is always directly across from the right angle.
In pictures, right angles are represented by a square.
<u><em>Therefore, the side with the hypotenuse is side 3</em></u>, because we can see that the angle between side 1 and side 2 is the right angle, and the hypotenuse would be directly across.
<u><em>For more information, see:</em></u>
brainly.com/question/21440624
<u><em>For information about parts of a right triangle, see:</em></u>
brainly.com/question/22137749
Image = other parts of a right triangle: