In this page we practice solving different triangle problems using area formulas, the Pythagorean formula, and angle rules.

Example 1 – Area of a Right Triangle

Base = 1 m
Height = 2 m

Area = (1/2)(1)(2)

Area = 1 m²

Example 2 – Area of an Obtuse Triangle

Base = 7 cm
Height = 6 cm

Area = (1/2)(7)(6)

Area = 21 cm²

Example 3 – Area of an Acute Triangle

Base = 6
Height = 4

Area = (1/2)(6)(4)

Area = 12 square units

Example 4 – Pythagorean Formula

A right triangle has sides 6 and 8.

Find the hypotenuse.

x² = 6² + 8²

x² = 36 + 64

x² = 100

x = 10

Example 5 – Finding a Missing Side

A right triangle has hypotenuse 5 and one side 3.

5² = x² + 3²

25 = x² + 9

x² = 16

x = 4

Example 6 – Finding a Missing Interior Angle

Two angles are 60° and 80°.

60 + 80 + x = 180

x = 40°

Example 7 – Exterior Angles

Two exterior angles are 120° and 120°.

120 + 120 + x = 360

x = 120°

Practice

• More Examples
• Take the Quiz

Continue Learning

1. Types of Triangles
2. Triangles (Basics)
3. Sum of Angles of a Triangle is 180° (Proof)
4. Find the Missing Angle of a Triangle
5. Sum of Exterior Angles of a Triangle (Proof)
6. Exterior Angle Theorem of a Triangle
7. Two Exterior Angles at a Vertex are Equal (Proof)
8. Two Exterior Angles are Equal at a Vertex (Quick Proof)

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