What is a triangle?

Definition

A triangle is a shape with three straight sides and three angles. The angles always add up to 180°.

Example

An equilateral triangle has three equal sides and three 60° angles.

Tip

To find a missing angle, subtract the other two from 180°.

Practise it

• Learn it visually: Angles in a Triangle (interactive lesson)
• Worksheets: Area of rectangles, triangles and parallelograms (Grade 6)
• Online maths practice

Quick check: try these

Work each one out on paper, then tap the question to see the answer.

1. The area of a triangle with base 14 cm and height 9 cm is (cm²)

   Answer: 63

2. The area of a rectangle 11 cm by 2 cm is (cm²)

   Answer: 22

3. The area of a rectangle 8 cm by 12 cm is (cm²)

   Answer: 96

4. The area of a rectangle 6 cm by 3 cm is (cm²)

   Answer: 18

Learn it in depth

Triangle is part of Pythagoras Theorem for Class 7: notes, formulas, solved examples with every step, common mistakes and ten practice questions with answers. Want a teacher to go through it with you? See Class 7 maths tuition.

Related words

Angle, Pythagorean theorem