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Right Triangle Area

Part of the Triangles section of Coddy's Geometry journey. Lesson 19 of 63.

A right triangle comes with its height built in. Its two legs, the sides that meet at the right angle, stand at right angles to each other. So one leg is the base and the other is the height.

$Right triangle PQR with legs 8 and 6 and longest side 10$

Here the legs are 8 and 6, so A = 1/2 × 8 × 6, which is 24. The longest side, 10, is slanted: it is not the height for either leg, so it plays no part in the area.

Challenge

△ABC has a right angle at A. Find its area, 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

1Sides and Names

Three Sides, Three Corners Sorting by Sides Naming by Angles Ticks into Equations The Longest Side Recap: Sorting Triangles

4Area of a Triangle

Half the Rectangle Height Is Not a SideRight Triangle AreaFinding 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

2The Triangle Inequality

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

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 Triangle Right Triangle Perimeter Recap: Two Tools