Year 6 · Maths · Shape · Lesson 1
Missing angles
Find missing angles on straight lines, around a point, vertically opposite, and in triangles and quadrilaterals, giving reasons.
20-minute video lesson
Teaching, worked examples and 20 practice questions solved step by step.
Watch free for a monthWhat your child will learn
- Use angles on a line and at a point
- Use vertically opposite angles
- Find angles in triangles
- Find angles in quadrilaterals
- Give reasons
The method
- What shape or line?
- Choose the fact.
- Subtract the known angles.
- Give your reason.
Key words: angle, straight line, vertically opposite, triangle, quadrilateral.
Worked examples
The first three practice questions from the lesson, with every step.
Question 1
Find the size of angle x. Give a reason.
- Step 1: Look at the diagram
- Step 2: Angles on a straight line add up to 180°.
- Step 3: x = 180° − 35° = 145°
Answer: x = 145°
Question 2
Find the size of angle x. Give a reason.
- Step 1: Look at the diagram
- Step 2: Angles on a straight line add up to 180°.
- Step 3: x = 180° − 140° = 40°
Answer: x = 40°
Question 3
Find the size of angle x. Give a reason.
- Step 1: Look at the diagram
- Step 2: Angles on a straight line add up to 180°.
- Step 3: x = 180° − 60° − 45° = 75°
Answer: x = 75°