SUBJECT: MATHEMATICS
CLASS: JSS 3
DATE:
TERM: 2nd TERM
WEEK FOUR
TOPIC: GEOMETRY CONTD
Areas and Volumes of similar shaped
Scale Factor (Length Ratio)
P 9cm Q
A B
2 6cm
D 3 C
S R
Scale factor = 9 or 6 = 3
3 2 1
Area factor = (Scale factor)2
= (3/1)2 = 9/1 or 9.1
If the ratio of the length is X : Y
Then the ratio of the area is X2 : Y2
Example 1:
In the diagram below, if the area of triangle ABC is 48cm2, find the area of triangle XYZ to 3s.f
A X
550
650 600 600
B 12cm C Y 4cm Z
Solution
© Lesson Notes All Rights Reserved 2023