A) Diameter = 18"
Circumference = pi x Diameter = pi x 18 = 56.52"
Area = pi x radius^2 = pi x 81 = 254.34 sq. inches
B) Radius = 5 cm
Circumference = pi x Diameter = 10pi cm
Area = pi x radius^2 = 25pi square cm
C) Area = 64pi square cm
Radius = 8 cm
Diameter = 16 cm
Circumference = pi x Diameter = 16pi cm
OR (in case you wanted it exactly as you wrote it)
Area = 64 square cm
Radius = 4.51 cm
Diameter = 9.03 cm
Circumference = pi x Diameter = 28.35 cm
D) Diagonal = Diameter = sq root of (a^2 + b^2) = sq root (81+144) = 15 cm
Circumference = pi x Diameter = 47.10 cm
Area = pi x radius^2 = 23.55 square cm
Hope I helped
Don't Forget to say thanks
