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Maths

Further trigonometry - Higher

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The area of a triangle

Area of triangle ABC = 1/2ab sin C

or, 1/2ac sin B

or, 1/2bc sin A

We can use this formula when we are given two sides and the included angle.

Question
image: triangle with a 42 degrees angle

Find the area of triangle ABC.

toggle answer

Answer

Area = 12.4cm2

The area of the triangle is

1/2 × 5.2 × 7.1 x sin42 = 12.4cm2

Remember to show all your working. It is easy to make a mistake when using your calculator, and you will not get any marks for a wrong answer.

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