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Geometry & MeasuresIntroduction

No Height? No Problem!

Part of Area of Triangle (Trig) — GCSE Mathematics

This introduction covers No Height? No Problem! 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 1 of 3 in this topic. Use this introduction to connect the idea to the wider topic before moving on to questions and flashcards.

Topic position

Section 1 of 3

Practice

12 questions

Recall

2 flashcards

No Height? No Problem!

The usual area formula (1/2 × base × height) needs the perpendicular height. But what if you only know two sides and the angle between them? The trig area formula saves the day!

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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.

The FormulaWorked Example

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

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

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The Formula