in geometry, two objects are similar when one is a scale model of the other. similar shapes
TRANSCRIPT
In geometry, two objects are similar when one is a scale model of the other.
SIMILAR SHAPES
These two triangles appear to be similar….
SIMILAR SHAPES
SIMILAR SHAPES
These two are NOT similar….
How do you check that triangles are similar?
SIMILAR TRIANGLES
We need to compare CORRESPONDING sides….
SIMILAR TRIANGLES
….or corresponding angles.
SIMILAR TRIANGLES
Corresponding angles will be equal.
26
12 2
4
8 2
5
10
Looking for a scale factor
8
10
6
15
912
SIMILAR TRIANGLES
These two triangles are similar. What is the scale factor?
8
10
6
15
912
SIMILAR TRIANGLES
We really only need to use one pair of corresponding sides.
SF = 12 ÷ 8 = 1.5
SIMILAR TRIANGLES
Are these triangles similar?
d
c
b
a adbc
4
6
6
8
8
10
Does the following apply?
Try this neat method...
If this is true, similarity applies
4
6
6
8
8
10
Lets check...
So these are not similar triangles
88106
The two triangles are similar. Use the cross multiplying method to determine the missing value x.
12
X
15
18
x
18
15
12
27012
151812
x
x
5.22
12270
x
x