A circle is a round 2D shape which has no sides or corners.
Radius: It is the distance from the centre of the circle to any point on its edge(boundary of the circle).
For the circle shown above, O is the centre of the circle and point A is on the edge.
OA is the radius of the circle.
Diameter: The diameter is the distance across the middle of the circle.
For the circle shown above, AB is the line passing through the centre O.
AB is the diameter of the circle.
Note: The diameter of a circle is twice the radius.
Work out the radius of the circle whose diameter is 15 cm.
Solution: Given the diameter of the circle d = 15 cm
Let the radius of the circle be r.
Diameter is twice the radius.
d = 2 × r
r = d ÷ 2
r = 15 ÷ 2
r = 7.5 cm
Radius of the circle is 7.5 cm.
Circumference: It is the distance around the circle. For example, if you take a wire of length 5 cm and bend it to form a circle, the circumference of the circle formed is the total length of the wire which is 5 cm.
To calculate the circumference of a circle, all we need to know is the radius of the circle and remember the formula, which is:
Circumference of the circle = 2 × π × r
For the formula use π = 3.14 or π = 22/7
Area: It is the total region covered inside the boundary of a circle, and is measured in square units.
To calculate the circumference of a circle, all we need to know is the radius of the circle and remember the formula, which is:
Area of Circle = π × (r)²
Amber got a frisbee as a birthday present. The diameter of the frisbee is 28 cm.
Find the circumference and area of the frisbee. Use π = 22/7
Solution:
Diameter is twice the radius, so
Radius of frisbee = 28÷2 = 14 cm
Circumference of frisbee = 2 × π × r
= 2 × 22⁄7 ×14
= 44 × 2
= 88 cm
Area of frisbee = π × (radius)²
= 22⁄7 × 14²
= 22⁄7 × 196
= 616 cm²
Semicircles are simply half of a circle. If you divide a circle into two exact parts, then each part is called a semicircle.
Circumference of a semicircle is the total length along its boundary, which is the sum of half the circumference of the circle and twice its radius.
Circumference of semicircle = Half of circumference of circle + 2 × r
= 1⁄2 × 2 × π × r +2 × r
= π × r + 2 × r
Area of semicircle = Half of the area of the circle
= 1⁄2 × π × (r)²
Work out the circumference and area of the shape shown below. Use π=22⁄7
Solution: The shape shown above is a semicircle of radius 21 cm.
So r = 21 cm
Circumference of the shape = π × r +2 × r
= 22⁄7 × 21 +2 × 21
= 66+42
= 108 cm
Area of the shape = 1⁄2 × π × (r)²
= 1⁄2 × 22⁄7 × (21)²
= 693 cm²
What counts as a "good" score will vary depending on the school you want to attend. The standardized 11 Plus test score average across the country is roughly 100. The highest average in some areas is 111. The lowest scores would often fall between 60 and 70, while the highest scores would normally fall between 130 and 140. To achieve excellent marks on 11+ Maths Exams, practice 11+ Maths topic-wise questions.
The best way to prepare for the 11+ Maths Exam is by practicing 11+ Maths topic-wise questions regularly.
Maths online subscriptions are “Non-Refundable“. No refunds can be issued for any reason. This is because of the nature of digital products.
You should, therefore, make sure that the Maths online subscriptions fulfil your needs before you subscribe.
As these are digital products, we advise parents to go through our Free Past Papers provided on our website and once decided they can buy subscriptions.
The majority of the 11 Plus Maths questions are mathematical problem-solving, where pupils need to understand and apply mathematical concepts. With regular practice of 11+ Maths Topic-wise questions, you will pass the 11-plus Maths Exam with a high score.
The children must master the following topics for the 11 plus exams
Get 10,000+ Topic-wise questions by subscribing to our 11+ Maths Topic-wise questions. These questions are collected from 180+ Maths past papers.
11 Plus Maths Past Papers Subscription
Any PiAcademy Memberships are for 1 year (366 days), We give Instant unlock to all exam Resources So that you can plan your 11+ Preparation according to your convenience and as per our Planner Spreadsheets.
Hurry! 11+ Exams are approaching in 6 months. High competition. Most parents fail to do structured planning for the 11+ Exam preparation.
Get a plan and strategy from 11+ Expert Tutors. Avoid the common mistakes that other parents make.
© 2014 - 2024 PiAcademy Limited, All Rights Reserved