Question

find (a) the area and (b) the circumference of each circle using π=3.14. Round to the hundredths' place. 1. the diameter of the circle is 9.5cm. 2. the radius of the circle is 4cm.

Answer 1

area = pi x r^2

circumference = 2x pi x r or pi x d

1st one diameter = 9.5 cm

so radius = 9.5/2 = 4.75

area = 3.14 x 4.75^2 = 70.85 square cm

circumference = 3.14 x 9.5 = 29.83 cm

2nd one radius = 4

area = 3.14 x 4^2 = 50.25 square cm

circumference = 2 x 3.14 x 4 = 25.12 cm

Answer 2

28a)  area = π (r^2) = π (4.75^2) = 70.84625 cm^2
28b)  circumference = πD = π (9.5) = 29.83 cm
29a)  area = π (r^2) = π (4^2) = 50.24 cm^2
29b)  circumference = πD = π (8) = 25.12 cm