This mixed practice stop brings together 1 topics from Primary 6 Circle: Mixed practice. Nothing on the question says which topic it comes from, so choosing the method is part of the skill. In the lesson. So read the question, and know which one it wants.
Lesson video, with the working
Circle area and perimeter questions
2 min 44 s
The film teaches 1 question. The question shows first; its working is written as the film explains it.
A semicircle of diameter 20 cm sits on top of a square of side 20 cm. Find the total area of the figure. (Take π = 3.14.)
Total area = 400 + 157 = 557 cm²
Ans: 557 cm²
How to solve it
Read what the question asks for. Perimeter is how far round, and area is how much is inside.
Area uses the radius. The semicircle's diameter is 20 centimetres, so its radius is 10 centimetres.
Square: 20 times 20 is 400 square centimetres.
Semicircle: a half, times 3.14, times 10, times 10, is 157 square centimetres.
Add the areas of joined shapes: 400 plus 157 is 557 square centimetres.
If it's asking for perimeter, remember we do not include the edge where the 2 shapes meet. If it's asking for area, everything inside a joined figure is included. So read the question, and know which one it wants.
Practice questions with worked solutions
Questions 1 and 5 are free to try. The other 9 open in the free trial, each with its full working.
How do you tackle P6 circle mixed practice questions?
Here area and perimeter questions are mixed together, so the first job is to decide which one the question wants.
What your child learns here
Here area and perimeter questions are mixed together, so the first job is to decide which one the question wants. It draws on all three Primary 6 circle outcomes: whole circles, semicircles and quarter circles, and composite figures.
Decide from the question's words whether it wants a distance round or the space inside.
Use the radius for an area and the diameter for a circumference, halving or doubling first as needed.
Count every part of a joined figure for area, but leave out the join for perimeter.
Treat a piece bitten out of a shape as area removed, while its curved edge becomes part of the perimeter.
Work back from a given arc length to the radius before finding an area.
Does the answer make sense?
Your child should match the unit to the question: a distance round or a length of wire is in cm or m, while the space inside is in square units. When a piece is only added to a square or rectangle, the area must be more than that shape alone; when only cut away, less.
How to practise these questions
This set mixes the Circles chapter's question types, so the first job is deciding whether area or perimeter is being asked. Basic questions train that choice on simple figures. Intermediate questions add notches, pieces that are cut and moved, and arcs that give away the size of a shape. Challenge questions fit tiles or count turns of a roll, and when your child is stuck, read the written step-by-step solution.
Questions parents ask
How does my child know whether to find area or perimeter? From the words of the question. Fence, border, wire, ribbon and distance round mean perimeter; paint, cover, tiles and space inside mean area. Ask your child to underline that word before starting.
Why practise circle questions mixed together? Exam questions do not say which page of the chapter they come from. Mixing the kinds makes the first decision, area or perimeter, part of the practice.
Is P6 circle practice available? Yes. Question 1 is free to try with its working, and members can practise the full mixed circles set, each question with a worked solution.
