Semicircle





In this page semicircle we are going to see how to find area and perimeter (circumference) of a semi-circle. To understand this topic much better we have given different kinds of example problems.

Semicircle is exactly half the entire circle.

Area of Semi-circle  = (1/2) Π r²

Here r represents the radius of the circle. Now let us see example problems based on the above formula.

Example 1:

Find the area of the semi-circle whose radius is 7 cm.

Solution:

Area of Semi-circle  = (1/2) Π r²

  Here r= 7 cm and Π = 22/7

           = (1/2) x (22/7) x 7²

           = (1/2) x (22/7) x 7 x 7

           = 1 x 11 x 7

           = 77 cm²


Example 2:

Find the area of the semi-circle whose radius is 3.5 cm.

Solution:

Area of Semi-circle  = (1/2) Π r²

  Here r = 3.5 cm and Π = 22/7

           = (1/2) x (22/7) x (3.5)²

           = (1/2) x (22/7) x 3.5 x 3.5

           = 1 x 11 x 0.5 x 3.5

           = 19.25 cm²


Now let us see formula to find the perimeter (circumference) of a semi-circle.

Perimeter of semi-circle = Πr

Example 1 :

Find the circumference of the semi-circle whose diameter is 7 cm.

r = diameter/2

r = 7/2

r = 3.5

Now we can apply the formula

Circumference of semi-circle = Πr

here r = 3.5 and Π = 22/7

               = (22/7) x 3.5 

               = 22 x 0.5

               = 11 cm


Example 2 :

Find the circumference of the semi-circle whose diameter is 42 cm.

r = diameter/2

r = 42/2

r = 21

Now we can apply the formula

Circumference of semi-circle = Πr

here r = 21 and Π = 22/7

               = (22/7) x 21 

               = 22 x 3

               = 66 cm


Example 3 :

Find the circumference of the semi-circle whose diameter is 56 cm.

r = diameter/2

r = 56/2

r = 28

Now we can apply the formula

Circumference of semi-circle = Πr

here r = 28 and Π = 22/7

               = (22/7) x 28 

               = 22 x 4

               = 88 cm

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