⟨a⟩.Given that
Radius of the circle (r) = 21 cm
We know that
Area of a circle whose radius is r units is
πr² sq.units
Area of the given circle
⇛A = (22/7)×21² cm²
⇛A = (22/7)×21×21 cm²
⇛A = 22×3×21 cm²
⇛A = 1386 cm²
Answer: Area of the circle = 1386 cm².
⟨b⟩.Given that
Diameter of the circle (d) = 35 cm
Radius = Diameter/2
⇛Radius = 35/2 cm
Area of a circle whose radius is r units is
πr² sq.units
Area of the given circle
⇛A = (22/7)×(35/2)² cm²
⇛A = (22/7)×(35/2)×(35/2) cm²
⇛A = (22×35×35)/(7×2×2) cm²
⇛A = 11×35×5/2 cm²
⇛A = 1925/2 cm²
⇛A = 962.5 cm²
Answer: Area of the circle = 962.5 cm².
(or)
Diameter of the circle (d) = 35 cm
We know that
Area of a circle whose diameter is d units is πd²/4 sq.units
Area of the given circle
⇛A = (22/7)×(35)²/4 cm²
⇛A = (22/7)×(1225/4) cm²
⇛A = (22×1225)/(4×7) cm²
⇛A = (11×175)/2 cm²
⇛A = 1925/2 cm²
⇛A = 962.5 cm²
Answer: Area of the circle = 962.5 cm²
⟨c⟩.Given that
Circumference of the circle (C) = 484 cm
We know that
Circumference of a circle whose radius is r units is 2πr units
⇛2πr = 484
⇛2×(22/7)×r = 484
⇛(44/7)×r = 484
⇛r = 484×(7/44)
⇛r = 11×7
⇛r = 77 cm
Area of a circle whose radius is r units is
πr² sq.units
Area of the given circle
⇛A = (22/7)×(77)² cm²
⇛A = (22/7)×77×77 cm²
⇛A = (22×77×77)/7 cm²
⇛A = 22×77×11 cm²
⇛A = 18634 cm²
Answer: Area of the circle = 18634 cm²
(or)
Circumference of the circle (C) = 484 cm
We know that
Area of a circle whose circumference is C units is C²/4π units
Area of the circle
⇛A = (484)²/{4×(22/7)}
⇛A = (484×484)/(88/7)
⇛A = (484×484)×(7/88)
⇛A = 1639792/88
⇛A = 18634 cm²
Answer: Area of the circle = 18634 cm²
