Question

Areas of some circles are given below, find their diameters. 

i. 176 sq.cm 

ii. 394.24 sq. cm 

iii. 12474 sq. cm

Answer 1

i. Area of the circle =176 sq. cm .. .[Given] 

Area of the circle = πr² 

∴ 176 = (22/7) x r² 

∴ r² = 176 x (7/22) 

∴ r² = 56 

∴ r = √56 … [Taking square root of both sides] 

Diameter = 2r = 2√56 CM 

ii. Area of the circle = 394.24 sq. cm … [Given] 

Area of the circle = πr²

∴ Diameter = 2r = 2 x 11.2 = 22.4 cm 

iii. Area of the circle = 12474 sq. cm … [Given]

Area of the circle = πr² 

∴ 12474 = (22/7) x r²

∴ r² = 12474 x (7/22) 

∴ r² = 567 x 7 

∴ r² = 3969 

∴ r = 63 …[Taking square root of both sides] 

∴ Diameter = 2r = 2 x 63 = 126cm