Answers:
AREA OF A CIRCLE = pi x r^2
5m circle:
when it says 5 i think it means diameter so divide by 2 for radius
5/2 = 2.5
3.14 x 2.5^2=
3.14 x 6.25=
19.625m^2
50mm circle:
50/2= 25
3.14 x 25^2=
3.14 x 625=
1962.5mm^2
40in circle:
40/2= 20
3.14 x 20^2 =
3.14 x 400=
1256in^2
7ft circle:
7/2= 3.5
3.14 x 3.5^2=
3.14 x 12.25=
38.465ft^2
21mm circle:
21/2= 10.5
3.14 x 10.5^2=
3.14 x 110.25=
346.185mm^2
70cm circle:
70/2=35
3.14 x 35^2=
314 x 1225=
3846.5cm^2
Hope that helps :)