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. Use this page as part of a wider topic revision path rather than treating it as an isolated fact. It is section 2 of 4 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
The Formula
| Area | = (1/2) × a × b × sin C |
| Where | C 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 |
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?
Starting from Area = ½ × base × height, show how to derive the formula Area = ½ab sinC.
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