5.3.3

Area of a Triangle

Test yourself

Area of a Triangle

We can use the formula: area of a triangle = 12ab sin(C).

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Formula

  • Area of a triangle = 12ab sin(C) since the vertical height is b sin(C).
  • This formula can also be used to calculate the side length of a triangle whose area is known.
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Example

  • If we are given a triangle with two sides of 8cm and 10cm and the area is 20cm2, we can calculate the angle between the sides as follows:
    • 20 = 12 × 8 × 10 × sin(C)
    • 20 = 40 × sin(C)
    • sin(C) = 12
    • C = 30°

Jump to other topics

1Proof

2Algebra & Functions

2.1Powers & Roots

2.2Quadratic Equations

2.3Inequalities

2.4Polynomials

2.5Graphs

2.6Functions

2.7Transformation of Graphs

2.8Partial Fractions (A2 Only)

3Coordinate Geometry

4Sequences & Series

5Trigonometry

6Exponentials & Logarithms

7Differentiation

8Integration

9Numerical Methods

10Vectors

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