1. Similarity
Similarity
Similarity
Similarity
Similarity

2. Similar Not Similar

3. Equiangular Similar triangles 1 So..similar ---- 3 Enlarge 4.5
Scale factor k =
4.5 cm
3 cm 3
k = 1.5
x =
1.5 X
2.2cm
2.2cm
= 3.3 cm
x cm

4. Parallel lines So equiangular Similar triangles 2 So similar ---- 3
Slide them apart
Add new sizes
Enlarge
4.5
----
Scale factor k =
3 cm 3
k = 1.5
4.5 cm
2.2cm
2.2cm
x =
1.5 X
1.5 cm
= 3.3 cm
x cm
x cm

5. Parallel lines So equiangular Similar triangles 3 So similar ---- 2.2
Slide them apart
Add new sizes
Enlarge
3.3
Scale factor k =
----
3 cm
2.2
k = 1.5
y cm
2.2cm
3cm
y =
1.5 X
x cm
= 4.5cm
x = cm
3.3 cm
3.3 cm
x = 1.5

6. Parallel lines So equiangular Similar triangles 4 So similar ---- 4.5
3.3 cm
Identify corresponding sides
Reduce 3
----
Scale factor k =
4.5 cm
4.5
k = 2/3
3.3 cm
x =
2/3 X
3 cm
= 2.2 cm
x cm

7. Similar Area New area is K2 X the old area Maths homework tonight…
Enlarge Scale factor k = 2
New area is X the old 4
New area is X the old 22
New area is K2 X the old area

8. Similar Area New area is K2 X the old area Enlarge Scale factor k = 3
New area is X the old 9
New area is X the old 32
New area is K2 X the old area

9. Similar Area New area is K2 X the old area Maths homework tonight…
Reduction Scale factor k = ½
New area is X the old
New area is X the old ½2
New area is K2 X the old area

10. Similar Area 1 ---- 28cm2 3 Enlarged 6 Scale factor k = k = 2 Area is?
28cm2 6
Scale factor k =
---- 3
7cm2
k = 2
Area is
k2 X original
3 cm
6 cm
= 22 X as big
= 4X
7cm2
= 28cm2

11. Similar Area 2 ---- 9 Reduced 81cm2 6 Scale factor k = k = 2/3 Area is
k2 X original
= (2/3)2 X as big
9 cm
6 cm
= (4/9)X
81cm2
= 36cm2

12. Similar Volume New Volume is K3 X the old volume
Enlarge Scale factor k = 2
New volume is X the old 8
New volume is X the old 23
New Volume is K3 X the old volume

13. Similar Volume 1 K3 8 cm 200 24 cm ? Enlarge Scale factor k =24/8
New volume = X the old
= X 200ml 33
= X 200ml
= litres

14. Similar Volume 2 K3 K3 £1.62 £ 0.48 ? 6 cm 4 cm
Reduce Scale factor k = 4/6
k = 2/3
New price = X the old price K3 K3
New Volume = X the old Volume
= X £1.62
(2 /3) 3
= 8/27 X £1.62
= £ 0.48

15. 3 Formulae New Length = K1 X old length New Area = K2 X old area
New Volume = K3 X old volume