WJEC MATHEMATICS
INTERMEDIATE
SHAPE AND AREA
CIRCLES
1
Contents
Parts of a circle
Pi
Circumference of a circle
Area of a circle
Circles in compound Shapes
Credits
WJEC Question bank
http://www.wjec.co.uk/question-bank/question-search.html
2
Parts of a circle
To make this section easier, make sure you know all mathematical
terms for all parts of a circle.
Important link:
Pi
Pi is a ratio that links the circumference and the diameter
Even though pi as a decimal goes on forever, we can use 3.142 as
an approximation for calculations
3
Circumference of a circle
To calculate the circumference of a circle, use the following formula;
“Circumference of a circle is pi times diameter”
Example
Find the circumference of the following circle
Make sure your answer is to a
sensible number of decimal
places
Some questions will give you a radius instead of a diameter. You will
need to multiply by 2 before calculating the circumference.
4
Area of a circle
To calculate the area of a circle, use the following formula;
“Area of a circle is pi times the radius squared”
Example
Find the area of the following circle
Half the diameter to get the
radius
Remember the 'squared' units
for area
With this knowledge you can calculate the area of half a circle or
quarter of a circle.
5
Exercise G18
Find the area and circumference of the following circles.
1.
2.
3.
4.
Exam Questions G27
1.
2.
3.
6
4.
2.
7
Circles and Compound Shapes
Circles are often used in finding the area of compound shapes. See
the 'Area' booklet for more work on this skill.
Exam Questions G28
1.
2.
8
3.
4.
5.
9
6.
7.
10