Question

The circumference of a circle is 5.8mm.
Find the length of the diameter.
Give your answer rounded to 3 SF.

Answer 1

$\mathrm \red{Given : }$

$\mathsf{circumference \: of \: circle \: is \: = 5.8 \: mm}$

$\mathsf{2 \pi r = 5.8} \: \: \: \: \: \: \: \: \: \: \: \: \: \: \\ \\ \mathsf{ 2 \times \frac{22}{7} \times r = 5.8} \\ \\ \mathsf{r \: = \: \frac{5.8 \times 7}{22 \times 2} } \\ \\ \mathsf{r = \frac{40.6}{44} } \: \: \: \: \: \: \\ \\ \mathsf{r = 0.92 \: mm }$

$\\ \\ \mathsf{diameter \: of \: circle \: = \: 2 \times r} \\ \\ \mathsf{d = 2 \times 0.92} \\ \\ \boxed{ \mathsf{d = 1.84}}$

$\\ \mathsf \red{ \therefore \: length \: of \: diametre \: = 1.84 \: mm}$