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Area of Triangle

Middle School

Definition

The area of a triangle is half the product of its base and height.

Formulas

A = (1)/(2) × b × h

Basic formula: base × height ÷ 2

  • AArea of the triangle
  • bLength of the base
  • hHeight perpendicular to the base
A = (1)/(2)absin C

Formula using two sides and included angle

  • a, bLengths of two sides
  • CAngle between the two sides
A = √s(s-a)(s-b)(s-c)

Heron's formula (s = (a+b+c)/2)

Examples

Example 1

Find the area of a triangle with base 6cm and height 4cm.

A = (1)/(2) × 6 × 4 = 12cm²
Example 2

Find the area of a triangle with sides 5cm and 8cm, and included angle 30°.

A = (1)/(2) × 5 × 8 × sin 30° = 10cm²

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