Geometry & MeasuresDeep Dive

Why is Triangle Area = ½ × Rectangle?

Part of Area of Rectangles & Triangles · GCSE GCSE Mathematics revision

This deep dive covers Why is Triangle Area = ½ × Rectangle? within Area of Rectangles & Triangles for GCSE Mathematics. Revise Area of Rectangles & Triangles in Geometry & Measures for GCSE Mathematics with 12 exam-style questions and 6 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 3 of 8 in this topic. Use this deep dive to connect the idea to the wider topic before moving on to questions and flashcards.

Topic position

Section 3 of 8

Practice

12 questions

Recall

6 flashcards

Why is Triangle Area = ½ × Rectangle?

1 Draw a rectangle around any triangle

2 The triangle takes up exactly HALF the rectangle

3 So: Triangle = ½ × (base × height) = ½ × Rectangle

Keep building this topic

Read this section alongside the surrounding pages in Area of Rectangles & Triangles. That gives you the full topic sequence instead of a single isolated revision point.

The Key Formulas Worked Example 1: Rectangle What is Area?Worked Example 2: Triangle

Practice Questions for Area of Rectangles & Triangles

Which formula gives the area of a rectangle with length l and width w?

A. 2(l + w)
B. l + w
C. l × w
D. (1/2) × l × w

1 markfoundation

Explain why the area formula for a triangle uses the perpendicular height rather than the slant height.

2 markshigher

Quick Recall Flashcards

Triangle Area

Area = ½ × base × perpendicular height (A = ½bh)

Rectangle Area

Area = length × width (A = l × w)

12 questions on Area of Rectangles & Triangles — practise free

Instant marking, adaptive difficulty, and 6 spaced repetition flashcards. Free until your GCSEs.

Try PrepWise Free

The Key Formulas

Worked Example 1: Rectangle