Turbine patterns
This task is about continuing a pattern and describing a rule for the pattern.
The shapes above are called turbines. Each turbine has 3 blades. 

a) 
Draw in the next two shapes in this series.

b) 
Complete this table.

Shape number (s)

1

2

3

4

5

i) Number of little triangles in each blade

1

4


ii) Number of little triangles in the whole shape

3

12

c) 
Complete the rule for each row of the table. 

i) 
The number of little triangles in each blade of shape number
s = ______________________________


ii) 
The number of little triangles in the whole of shape number
s = ______________________________

d)  How many triangles would there be in shape number 8? __________ 