Geometry & MeasuresStudy Notes

Worked Example 2: Isosceles Triangle

Part of Properties of TrianglesGCSE Mathematics

This study notes covers Worked Example 2: Isosceles Triangle within Properties of Triangles for GCSE Mathematics. Revise Properties of Triangles in Geometry & Measures for GCSE Mathematics with 12 exam-style questions and 3 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 5 of 8 in this topic. Use this study notes to connect the idea to the wider topic before moving on to questions and flashcards.

Topic position

Section 5 of 8

Practice

12 questions

Recall

3 flashcards

Worked Example 2: Isosceles Triangle

An isosceles triangle has a top angle of 40°. Find the two base angles.

Step 1 Set up the equation

Let each base angle = x

40° + x + x = 180°

40° + 2x = 180°

Step 2 Solve for x

2x = 180° − 40° = 140°

x = 70°

Each base angle = 70°

Keep building this topic

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

Practice Questions for Properties of Triangles

What is the sum of the interior angles of any triangle?

  • A. 90°
  • B. 180°
  • C. 270°
  • D. 360°
1 markfoundation

Describe the key properties of an equilateral triangle. State two properties relating to sides and two relating to angles.

2 marksstandard

Quick Recall Flashcards

Triangle Angle Sum
Always 180°
Isosceles Triangle
Two equal sides, two equal angles

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