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Question
If the diameter of a semi-circular protractor is 14 cm, then find its perimeter.
Solution
Let AB be the diameter of the semi-circular protractor.
So, `AB=14 cm`
`"We know that perimeter of the semicircle" = 1/2 (2pi r)+2r .........(1)`
We have given the diameter of the protractor.
Therefore, radius of the protractor =`14/2`
So, radius of the protractor `=7`
Substituting the value of r in equation (1) we get,
Perimeter of the semi-circular protractor=`1/2(2pxx7)+2xx7`
Perimeter of the semi-circular protractor=`(pixx7)+14`
Substituting `pi=22/7` we get
`"Perimeter of the semi-circular protractor"=(22/7xx7)+14`
`"Perimeter of the semi-circular protractor"=22+14`
`"Hence Perimeter of the semi-circular protractor"'=36`
Therefore, perimeter of the semi-circular protractor is ` 36 cm`
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