Question

A. Choose the correct option:
1. If the perimeter of a semi-circle is 36 cm, then its radius is:
(i) 14 cm
(11) 7 cm
(iii) 21 cm
(iv) 3.5 cm​

Answer 1

Answer:

Option B is the answer for your question.

Proof is given in the attachment.

Note: π+2 = 22/7 + 2

= (22+ (7×2)) /7

= 36/7

Step-by-step explanation:

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Answer 2

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✤ Required Answer:

✒ GiveN:

• Perimeter of semi circle = 36 cm

✒ To FinD:

• Radius of the semi circle....?

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✤ How to solve?

Here, we have given the perimeter of a semicircle and we have to find the radius.

❍ First of all, we all know the formula for perimeter of a complete circle I.e the length of the boundary

• Perimeter of ○ = 2πr

Here, π is taken 22/7 for easy calculation and r is the radius of the circle.

❍ Now, We known that half of a circle is known as Semi circle. So, the perimeter must be half of perimeter of circle. But this is not true, We have to add the diameter (2 × radius) also, because perimeter means the entire boundary.

Length of curved part = 2πr/2 = πr

• Perimeter of Semi circle = πr + 2r = r(π+2)

So, By using this formula, let's solve the question$.$

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✤ Solution:

We have,

• Perimeter of semi circle = 36 cm

So, according to formula,

➝ r(π + 2) = 36 cm

➝ r(22/7 + 2) = 36 cm

➝ r[(22 + 14)/7] = 36 cm

➝ r(36/7) = 36 cm

➝ r = 36 × 7 / 36 cm

➝ r = 7 cm

♠️ Hence, The correct option is (ii)

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