Geometry & MeasuresKey Facts

The Formula

Part of Area of Triangle (Trig)GCSE Mathematics

This key facts covers The Formula within Area of Triangle (Trig) for GCSE Mathematics. Revise Area of Triangle (Trig) in Geometry & Measures for GCSE Mathematics with 12 exam-style questions and 2 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 2 of 3 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.

Topic position

Section 2 of 3

Practice

12 questions

Recall

2 flashcards

The Formula

Area= (1/2) × a × b × sin C
WhereC is the INCLUDED angle (between sides a and b)
Also written as(1/2)ab sinC or (1/2)bc sinA or (1/2)ac sinB

Keep building this topic

Read this section alongside the surrounding pages in Area of Triangle (Trig). That gives you the full topic sequence instead of a single isolated revision point.

Practice Questions for Area of Triangle (Trig)

What is the trigonometric formula for the area of a triangle with sides a and b and included angle C?

  • A. Area = ab sinC
  • B. Area = ½ab sinC
  • C. Area = ½ab cosC
  • D. Area = ½(a + b) sinC
1 markfoundation

Starting from Area = ½ × base × height, show how to derive the formula Area = ½ab sinC.

2 marksstandard

Quick Recall Flashcards

Trig Area Formula
Area = (1/2)ab sinC. The angle MUST be between the two sides you're using.
Area with Trig
Area = ½ab sin C

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