Question

1. Calculate the area of the circle having the following radius (r) or diameter (d) (π= 3.14) (a) Radius (r) = 3 cm (b) Diameter (d) = 5 cm (c) Radius (r) = 8 ft. (d) Diameter (d) = 12 cm (f) Diameter (d) = 20 km (g) Diameter (d) = 15 mm (i) Radius (r) = 16 yd​

Answer 1

The area of circle having radius 3cm is 28.27 cm², diameter 5cm is 19.63 cm², radius 8 ft is 201.06 ft², diameter is 113.1 cm², diameter 20 km is 314.16 km², diameter 15 mm is 176.71 mm² and radius 16 yd is 804.25 yd².

Given the radius and diamtere are (a) Radius (r) = 3 cm (b) Diameter (d) = 5 cm (c) Radius (r) = 8 ft. (d) Diameter (d) = 12 cm (f) Diameter (d) = 20 km (g) Diameter (d) = 15 mm (i) Radius (r) = 16 yd​.

We will calculate the area of circle by using the formula A=πr² or π(d/2)².

(a) Radius (r)=3cm

The area of circle is

Area=π(3)²

Area =9π

Here, π=3.14, we get

Area =9×3.14

Area=28.27cm²

(b) Diameter (d)=5cm

The area of circle is

Area=π(5/2)²

Area =π(2.5)²

Area=6.25π

Here, π=3.14, we get

Area =6.25×3.14

Area=19.63cm²

(c) Radius (r)=8 ft

The area of circle is

Area=π(8)²

Area =64π

Here, π=3.14, we get

Area =64×3.14

Area=201.06ft²

(d) Diameter (d)=12cm

The area of circle is

Area=π(12/2)²

Area =36π

Here, π=3.14, we get

Area =36×3.14

Area=113.1cm²

(e) Diameter (d)=20km

The area of circle is

Area=π(20/2)²

Area =100π

Here, π=3.14, we get

Area =100×3.14

Area=314.16km²

(f) Diameter (d)=15mm

The area of circle is

Area=π(15/2)²

Area =56.25π

Here, π=3.14, we get

Area =56.25×3.14

Area=176.71mm²

(g) Radius (r)=16yd

The area of circle is

Area=π(16)²

Area =256π

Here, π=3.14, we get

Area =256×3.14

Area=804.25yd²

Hence, the area of circle having radius and diameter is  radius 3cm is 28.27 cm², diameter 5cm is 19.63 cm², radius 8 ft is 201.06 ft², diameter is 113.1 cm², diameter 20 km is 314.16 km², diameter 15 mm is 176.71 mm² and radius 16 yd is 804.25 yd².

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