1. a) The formula for the area of a parallellgram is base x height.
b) The circumference of a circle is 2 x π x r. Half of the circumference of a circle is π x r.
c) Half of the circumference of a circle is approximately equal to the length of the base of the parallellgram.
d) The height of the parallellgram is approximately equal to the radius of a circle.
e) The area of the parallellgram is the base, which is π x r, times the height, which is r, so the area of a circle equals π x r^2.
2. a) Radius = 5 cm
Radius squared = (5)^2 = 25 cm^2
Diameter = 5*2 = 10 cm
Area = 3*25 = 75 cm^2
b) Radius = 16/2 = 8 cm
Radius squared = 8^2 = 64 cm^2
Diameter = 16 cm
Area = 3*8^2 = 192 cm^2
3. a) Radius = 11 cm
Diameter = 22 cm
Area = 11^2*3.14 = 379.94 cm^2
b) 12/2 = 6 cm
Diameter = 12 cm
Area = 6^2*3.14 = 113.04 cm^2
