Question

Please help in the questions I have circled

Answer 1

see explanation

Explanation:

using the following formulae

circumference ( C) = πd ← d is the diameter and radius (r) =
`(d)/(2)`

(7)

given C = π , then d = 1 and r = 0.5

(8)

given C = 78.8 , then πd = 78.8 ( divide both sides by π )

d =
`(78.8)/(3.14)` = 25.10 and r =
`(25.10)/(2)` = 12.55

(9)

given d = 3.4 , then r =
`(3.4)/(2)` = 1.70 and

C = πd = 3.14 × 3.4 = 10.68