Question

EXERCISE 21B
1. Find the circumference of a circle whose radius is
(i) 28 cm

plss fast it is urgent​

Answer 1

Question:-

Find the circumference of a circle whose radius is 28 cm.

Answer:-

• The circumference of circle is 175.84 cm

To find:-

• Circumference of circle

Solution:-

$\blue{ \boxed{ \red{ \large{circumference = 2\pi \: r}}}}$

• The value of $\pi$is 3.14.

• Radius (r) = 28 cm

$\large{ : \implies \: circumference = 2 \times 3.14 \times 28}$

$\large{ : \implies circumference = 6.28 \times 28}$

$\large{ : \implies \: circumference = 175.84 \: cm}$

• The circumference of circle is 175.84 cm

Answer 2

Given

• Radius of the circle (r) = 28 cm

To find

• Circumference of the circle.

Solution

• Using the formula

$\large{\underline{\boxed{\tt{Circumference = 2πr}}}}$

$\tt:\implies\: \: \: \: \: \: \: \: {Circumference = 2 × \dfrac{22}{\not{7}} × \not{28}}$

⠀

$\tt:\implies\: \: \: \: \: \: \: \: {Circumference = 2 × 22 × 4}$

⠀

$\tt:\implies\: \: \: \: \: \: \: \: {Circumference = 44 × 4}$

⠀

$\tt:\implies\: \: \: \: \: \: \: \: {Circumference = 176cm}$

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$\large{\sf{\pink{Extra\: shots}}}$

‣ Area of a circle = πr²

‣ Area of a semi circle = $\dfrac{1}{2}$πr²

‣ Circumference of a semi circle = πrd