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Year 6 · Maths · Area, perimeter and volume · Lesson 1

Area of triangles and parallelograms

Calculate the area of triangles and parallelograms using base and perpendicular height, and solve reverse area problems.

Whiteboard video lesson: Area of triangles and parallelograms

22-minute video lesson

Teaching, worked examples and 20 practice questions solved step by step.

Watch free for a month

What your child will learn

  • Identify perpendicular height
  • Find the area of a parallelogram
  • Find the area of a triangle
  • Find a missing length from the area
  • Explain the formulae

The method

  1. Find base and perpendicular height.
  2. Choose the formula.
  3. Multiply (halve for a triangle).
  4. Units: cm².

Key words: area, triangle, parallelogram, base, perpendicular height.

Worked examples

The first three practice questions from the lesson, with every step.

Question 1

Find the area of a triangle with base 6 cm and perpendicular height 4 cm.

  1. Step 1: Find base and height
  2. Step 2: Area = 1/2 × base × height
  3. Step 3: = ½ × 6 × 4 = 12 cm²

Answer: 12 cm²

Question 2

Find the area of a triangle with base 10 cm and perpendicular height 3 cm.

  1. Step 1: Find base and height
  2. Step 2: Area = 1/2 × base × height
  3. Step 3: = ½ × 10 × 3 = 15 cm²

Answer: 15 cm²

Question 3

Find the area of a triangle with base 12 cm and perpendicular height 5 cm.

  1. Step 1: Find base and height
  2. Step 2: Area = 1/2 × base × height
  3. Step 3: = ½ × 12 × 5 = 30 cm²

Answer: 30 cm²