Draw circles of different radii on a graph paper. Find the area by cou

1.	Draw circles of different radii on a graph paper. Find the area by counting the number of squares covered by the circle. Also find the area by using the formula. (i) Find the area of the circle, if the radius is 4.2 cm. (ii) Find the area of the circle if the diameter is 28 cm.
Answer» (i) Radius of the circle r = 4.2 cm Area of the circle A = πr² sq. units = \(\frac{22}{7}\) x 4.2 x 4.2 cm² = 5.44 cm² (ii) Diameter of the circle d = 28 cm Radius r = \(\frac{d}{2}\) = \(\frac{28}{2}\) = 14 cm Area of the circle A = πr² sq.units = \(\frac{22}{7}\) x 14 x 14 cm² = 616 cm²

Draw circles of different radii on a graph paper. Find the area by counting the number of squares covered by the circle. Also find the area by using the formula. (i) Find the area of the circle, if the radius is 4.2 cm. (ii) Find the area of the circle if the diameter is 28 cm.

Answer»

(i) Radius of the circle r = 4.2 cm

Area of the circle A = πr² sq. units

= \(\frac{22}{7}\) x 4.2 x 4.2 cm²

= 5.44 cm²

(ii) Diameter of the circle d = 28 cm

Radius r = \(\frac{d}{2}\)

= \(\frac{28}{2}\)

= 14 cm

Area of the circle A = πr² sq.units

= \(\frac{22}{7}\) x 14 x 14 cm²

= 616 cm²