The Hypotenuse Sits Alone

You'll learnto identify the hypotenuse first, then use a² + b² = c² correctly.

In a right triangle the hypotenuse sits opposite the right angle and is the longest side, and a² + b² = c². Points leak in three places: assigning the hypotenuse to a leg, misusing the special-triangle ratios, and reporting a squared value or the wrong quantity of the triangle.

8 STEPS · 6 QUICK CHECKS · add for the hypotenuse, subtract for a leg · finish the problem · v2

a² + b² = c²

Before you start

What you're looking at

A right triangle with legs a and b and hypotenuse c, beside the theorem a² + b² = c² and a plan card.

The question

Which side is the hypotenuse, and do you add or subtract the squares?

Watch for

Watch the hypotenuse sit opposite the right angle as the longest side, alone as c.

What the symbols mean

a and b are the legs; c is the hypotenuse, opposite the right angle; the card holds the plan.

Step 1 / 8