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

Perimeter of semi circle = (Π + 2)r

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

Example 3 :

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

Solution :

r = diameter/2  ==>  r = 7/2  ==> r = 3.5

Now we can apply the formula

Circumference of semi-circle = (Π + 2)r

here r = 3.5 and Π = 22/7

  =  [(22/7)  + 2]x 3.5 

  =  (22+14) x 0.5

  =  36 x 0.5

  =  18 cm

Example 4 :

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

Solution :

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 5 :

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

Solution :

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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