Question

The perimeter of semi-circular protractor is 108cm.Find the diameter of protractor ​

Answer 1

Answer:

68.6 cm.

Explanation:

Given -

We know that,

Perimeter of a semi circle = 2πr / 2 = πr

Let the radius of the circle be r cm.

Therefore,

According to the question,

$perimeter \: of \: a \: semi - circular \: protactor \: = \: 108 \: cm.$

$= > \pi \times r = 108 \\ = > \frac{22}{7} \times r = 108 \\ by \: cross \: multiplying \: we \: get \: ... \\ = > r = \frac{108 \times 7}{22} \\ = > r \: = \: \frac{54 \times 7}{11} = 34.3 \: cm.$

Therefore diameter = 2×radius = 2×r = 2×34.3 = 68.6 cm.

____________❤

Some important formulae related to area and perimeter of a circle -

• Perimeter of a circle - 2πr cm.
• Area of a circle - πr^2
• Area of a hollow circular thing - π(R^2 - r^2),where R = external radius, r = internal radius.

Semicircle -

• Perimeter of a semi circle - πr
• Area of a semi circle - πr^2 /4

ђ๏קє tђเร ђєlקร ץ๏ย__❤✔️

Answer 2

Answer:

$\large\boxed{\sf{42.02\;cm}}$

Step-by-step explanation:

Given that

Perimeter of semicircular protactor = 108 cm

To find the diameter

Let the Radius is 'r'

We know that,

Perimeter will be equal to (πr + 2r)

Therefore, we get

$= >r( \pi + 2 ) = 108 \\ \\ = > r(3.14 + 2) = 108 \\ \\ = > 5.14r = 108 \\ \\ = > r = \frac{108}{5.14} \\ \\ = > r = 21.01$

Therefore, radius = 21.01 cm

Hence, diameter = 42.02 cm