Question

Work out the

circumference of a circle with diameter 1.8 cm.
Take pi to be 3.142 and give your answer to 1 decimal place.

Answer 1

5.7cm

Explanation:

circumference = π · d

(2πr)

{note: "d" is diameter; "r" is radius; "π" is pi}

we know our diameter (d) to be 1.8

let's plug this into our cicumference formula! :

π · d = circumference

(3.142) · (1.8)

3.142 · 1.8 = 5.6556

let's round our answer to 1 decimal place,

remember, if the next digit is ≥5 we round up; < 5 we keep the same

so, our answer is 5.7 cm

hope this helps!! have a lovely day :)

Answer 2

Explanation:

the circumference of a circle is

2×pi×r

with r being the radius, which is always half of the diameter.

r = 1.8 / 2 = 0.9 cm

circumference :

2×pi×0.9 = 1.8×pi = 1.8 × 3.142 = 5.6556 cm ≈ 5.7 cm