Question

5. Find the circumference of the circle whose radius is: (I)2•8cm(ii) 5.6 cm (iii) 7.0 cm 22 Take 1 = 7 쪽 (

Answer 1

Take circumference of circle =2πr and add r value

Answer 2

(I) r= 2.8 cm

$c = 2\pi \: r \\ = 2 \times \frac{22}{7} \times 2.8 \\ = 2 \times \frac{22}{7} \times \frac{28}{10} \\ = 22 \times \frac{4}{5} \\ = \frac{88}{5} \\ = 17.6 \: cm$

ii) r= 5.6 cm

$c = 2\pi \: r \\ = 2 \times \frac{22}{7} \times 2 \\ 5.6 \\ = 2 \times \frac{22}{7} \times \frac{56}{10} \\ = 22 \times \frac{8}{5} \\ = \frac{176}{5} \\ = 35.2\: cm$

iii) r= 7 cm

$c = 2\pi \: r \\ = 2 \times \frac{22}{7} \times 7 \\ = 2 \times 22 \\ = 44 \: cm$