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Right Triangle Perimeter

Part of the Triangles section of Coddy's Geometry journey. Lesson 54 of 60.

A perimeter needs all three sides. If a right triangle gives you only the two legs, find the hypotenuse first with Pythagoras, then add.

$Right triangle PQR with legs 8 and 6$

Here the legs are 8 and 6, so the hypotenuse is $\sqrt{64+36} = 10$ and the perimeter is $8+6+10 = 24$ . Two steps: Pythagorean theorem, then Perimeter. If the hypotenuse comes out as a root, the perimeter keeps it: legs 1 and 2 give 3 + √5.

Challenge

△ABC has a right angle at A and legs 24 and 18. Find its perimeter, then press Check.

Try it yourself

$Find the marked part of the figure$

Find the marked part of the figure

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Triangles

1The Triangle Inequality

Can Three Sticks Meet?Exactly Reaching The Range of the Third Side Recap: The Third Side

4Area of a Triangle

Half the Rectangle Height Is Not a Side Right Triangle Area Finding the Height Any Side Can Be the Base Recap: Area

7Is It Right?

The Converse Testing a Triangle Acute or Obtuse?Sorting by the Test Recap: Right or Not

10Scale in the World

Shadows Across the River Nested Triangles A Side with an Expression Recap: Scale in the World

2Sides and Names

Sorting by Sides The Longest Side Ticks into Equations Recap: Sorting Triangles

5The Pythagorean Theorem

Squares on the Sides Finding the Hypotenuse Pythagorean Triples When It Is Not Whole Recap: The Hypotenuse

8Special Right Triangles

The 45-45-90 Triangle Legs from the Hypotenuse The 30-60-90 Triangle All Three Sides Which Triangle Is It?Recap: Special Triangles

11Two Tools at Once

Height of an Isosceles Area from the Height The Equilateral TriangleRight Triangle PerimeterRecap: Two Tools