Question

Perimeter of semi circular protactor with diameter 14cm is

22 cm

36 cm

29 cm

14 cm
​

Answer 1

Answer :-

Perimeter of semi circular protactor with diameter 14cm is 36cm.

[ Option b. 36cm ]

Step-by-step explanation :-

To Find,

• The perimeter of the semi-circular protactor

Solution,

Given that,

• Diameter of protactor = 14cm

Figure,

$\setlength{\unitlength}{1cm}\begin{picture}(0,0)\thicklines\qbezier(2.3,0)(2.121,2.121)(0,2.3)\qbezier(-2.3,0)(-2.121,2.121)(0,2.3)\put(-2.3,0){\line(1,0){4.6}}\put(-2.3,-0.3){\line(1,0){4.6}}\put(-2.3,-0,4){\line(0,1){0,3}}\put(2.3,-0,4){\line(0,1){0,3}}\put(-0.2,-0.6){ \sf \: 14cm }\end{picture}$

According the question,

First we need to find out the radius of the protactor,

As we know that,

$\dag \: \: \underline{ \boxed{ \red{ \sf{radius = \frac{diameter}{2}}}}}$

$\longrightarrow \: \sf{Radius = \dfrac{14}{2}} \\ \\ \\ \longrightarrow \sf{Radius = \cancel{ \dfrac{14}{2}}} \\ \\ \\ \frak{ \pink{Radius = 7cm}}$

Hence, radius of protactor is 7cm.

Now, Perimeter of protactor,

As we know that,

$\dag \: \: \underline{ \boxed{ \red{ \sf{Perimeter \: of \: semi-circle \: = \: r(\pi + 2)}}}}$

$\sf{\longrightarrow \: r(\pi + 2)} \\ \\ \\ \sf{\longrightarrow \: r \bigg( \dfrac{22}{7} + 2 \bigg)} \\ \\ \\ \sf{\longrightarrow \: r \bigg( \dfrac{22}{7} + \dfrac{2}{1} \bigg)} \\ \\ \sf{\longrightarrow \: r \bigg( \dfrac{22 + 14}{7} \: \bigg)} \\ \\ \\ \sf{\longrightarrow \: r \bigg( \dfrac{36}{7} \: \bigg)} \\ \\ \\ \sf{\longrightarrow \: 7 \times \dfrac{36}{7}} \\ \\ \\ \sf{\longrightarrow \: \cancel{7} \times \dfrac{36}{ \cancel{7}}} \\ \\ \\ \frak{\longrightarrow \: \pink{36cm}} \: \: \: \bigstar$

∴ The perimeter of semi-circular protactor is 36cm.

Answer 2

Given :

• Diameter of the protractor = 14 cm

To find :

• The perimeter of the protractor

Solution :

Here we have a semi circular object. First we will find the radius of the semi circle as diameter is already given:-

• Radius = Diameter/2

→ Radius = 14/2

→ Radius = 7 cm

Now when we have the radius we can find the perimeter of the semi circle by using the following formula:-

• Perimeter = r(π + 2)

★ Here:-

• r = radius
• π = 22/7

→ Perimeter = 7(22/7 + 2)

→ Perimeter = 7(22 + 14/7)

→ Perimeter = 7(36/7)

→ Perimeter = 36 cm

Answer :

• The perimeter of the semi circle = 36 cm