IGCSE Maths / Further trigonometry

Finding a side or an angle from a given area

Edexcel International GCSE Maths (4MA1), chapter 25: Further trigonometry, specification point 4.8e. Part of the full course.

Read the revision notes · IGCSE Maths past papers

The triangle area formula, 1/2ab sin C, can be rearranged to find a missing angle or side. When finding an angle, check whether the question rules out the second possible angle.

More lessons in Further trigonometry

• The sine rule: finding a missing side
• The sine rule: finding a missing angle
• The ambiguous case of the sine rule
• The cosine rule: finding a missing side
• The cosine rule: finding a missing angle
• Choosing between the sine rule and the cosine rule
• Area of a triangle using half ab sin C
• Area of a segment
• The angle between a line and a plane
• Trigonometry in pyramids and cones
• Problem solving in three dimensions