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GR.8.4

Problem solving - similarity

Use similarity to solve problems

5 hand-picked video lessons for this topic, each checked for relevance and clarity, graded by difficulty and labelled by depth. Press play to watch — nothing loads from YouTube until you do.

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Grade 4–8 Core 🇬🇧 UK

Similar Triangles - GCSE Maths

1st Class Maths 356K views

Excellent GCSE lesson on connected and overlapping similar triangles in parallel lines.

Jump to 0:10Important properties of similar triangles 2:40Example 1 - Connected triangles in parallel lines 5:34Example 2 - Connected triangles in parallel lines 7:51Example 3 - Overlapping triangles in parallel lines 11:42Example 4 - Overlapping triangles in parallel lines 13:10Example 5 - With ratios

Grade 3–6 Core 🇬🇧 UK

GCSE Maths - Similar Shapes (2026/27 exams)

Cognito 239K views

Clear, concise walkthrough of similar shapes and using scale factors to find missing lengths.

Jump to 0:39Finding Unknown Side Lengths 1:00Example 1: Calculating the Scale Factor 1:40Example 1: Using the Scale Factor (Enlargement)2:06Example 2: Calculating Missing Lengths in Similar Triangles

Grade 6–9 Stretch 🇬🇧 UK

#EP2 Similar Shapes with Ratios - Can You Solve These GCSE Questions? | Grade 6+ Problem Solving

The GCSE Maths Tutor 26K views

Problem-solving practice combining similar shapes with ratios on exam questions.

Grade 4–7 Core 🇺🇸 US

Similar Triangles

The Organic Chemistry Tutor 902K views

Lots of worked similar-triangle examples using proportions to find missing sides.

Grade 4–7 Core 🇺🇸 US

Similarity example problems | Similarity | Geometry | Khan Academy

Khan Academy 750K views

Two clear worked similarity problems finding unknown lengths with proportions.