Area of Circles

0

20

40

60

80

0 1 2 3 4 5Radius (m)

Are

a (m

2 )Area of a circle 2πrARadius r (m) 0 1 2 3 4 5Area A (m2) 0 3.1 12.6 28.3 50.3 78.5

when r = 2.5

A = 20 (to 2sf)

when A = 30

r = 3.1 (to 2sf)

Cooling Cup of Coffee

0

20

40

60

80

100

0 10 20 30 40 50Time (minutes)

Tem

per

atu

re (

deg

rees

C)

Temperature of a cup of coffee

After 12 minutes

the temperature is 56C (nearest ).

The temperature is 70C

after 6 minutes(nearest minute).

Time (min) 0 5 10 15 20 25 30 35 40 45Temperature (C) 84 72 60 51 42 35 30 25 21 18

Drawing Graphs

• Draw up a table of values using data or values calculated from a formula.

• Put the independent variable on the horizontal axisand the dependent variable on the vertical axis.

• Use suitable scales, covering the range of values.Draw a large graph using a sensible scale.2 cm representing 1, 2, 5, 10, 20, 50, 100, 200, 500,……

• Plot the points.Draw the best fit curve or straight line through them.

• Add title and labels (including units if there are any).