Perimeter of Semicircle
The perimeter of the semicircle is the sum of half of the given circle's circumference and the diameter of the circle. A semicircle as the name suggests is made of two words semi and circle which is a twodimensional shape that represents half a circle. Like all twodimensional shapes, you will learn how to calculate the perimeter of the semicircle. Stay tuned to learn how to use its formula using solved examples!!!
1.  What is the Perimeter of Semicircle? 
2.  Formula of Circumference of Semicircle 
3.  How to Find the Perimeter of Semicircle? 
4.  FAQs on Perimeter of Semicircle 
What is the Perimeter of Semicircle?
The perimeter of a semicircle also known as the circumference of the semicircle is defined as the total length of the boundary of the semicircle. A semicircle is a halfcircle that is not a polygon. Thus, the perimeter of the semicircle is given by summing the length of the diameter of the original circle and halving the circumference of the original circle. Since a circle is a twodimensional shape, thus, the circumference of the semicircle will also lie in a twodimensional plane only. The unit of the perimeter of the circle is given in the units like "inches", "feet", "meters" or "centimeters" etc.
Formula of Circumference of Semicircle
Consider the below semicircle where AB is the diameter of the semicircle. Let the perimeter of the semicircle be "P".
The perimeter of the semicircle is given as P = Half of Circumference of original circle + Length of Diameter.
Circumference of circle = 2πr
Half of the circumference of the circle = (1/2) × Circumference of circle = (1/2) × 2πr = πr = π(d/2)
Length of diameter = d = 2r
The circumference of the semicircle is P = C = πr + d = πr + 2r = (π + 2)r units
In terms of diameter, the circumference of the semicircle is P = C = π(d/2) + d.
How to Find the Perimeter of Semicircle?
The steps to determine the perimeter of the semicircle are:
 Step 1: Determine the product of π and the radius of the semicircle.
 Step 2: Find the diameter of the semicircle.
 Step 3: Add the values obtained in the above two steps.
 Step 4: The value thus obtained is the perimeter of the semicircle.
Example: Find the circumference of a semicircle whose radius is 7 units. (Use π = 22/7)
Solution: Given that: Radius of the semicircle is 7 units. Let the perimeter of the semicircle is "P".
Thus, the perimeter of the semicircle is P = πr + 2r ⇒ P = (22/7 × 7) + (2 × 7)
= (22 + 14) units. Thus, P = 36 units
∴ The perimeter of semicircle is 36 units.
Solved Examples on Perimeter of Semicircle

Example 1: Find the circumference of the semicircle having a diameter of 42 inches. (Use π = 22/7)
Solution: The given dimension of diameter of semicircle = 42 inches. Let the circumference of the semicircle be "C".
Circumference of semicircle, C = π(d/2) + d ⇒ C = (22/7 × 42/2) + 42
= (66 + 42) inches. Thus, C = 108 inches
∴ The circumference of the semicircle is 108 inches.  Example 2: What is the area of the semicircle if the perimeter of the semicircle is 144 units. (Use π = 22/7)
Solution: Given the perimeter of the semicircle is 144 units. Let the radius of the semicircle be "r" and the area of the semicircle be "A".
As we know, perimeter of semicircle = (π + 2)r units ⇒ P = (π + 2)r = (22/7 + 2)r = 144 units
⇒ (36/7)r = 144. Thus, r = 144 × (7/36) = 28 unitsWe know that the area of semicircle, A= (πr^{2})/2
⇒ A = (πr^{2})/2 = (22/7 × (28^{2}))/2 = 1232 square units∴ The area of the semicircle is 1232 square units.
FAQs on Perimeter of Semicircle
What Do You Mean By Perimeter of Semicircle?
The perimeter of the semicircle is defined as the sum of half of the given circle's circumference and the diameter of the circle. The perimeter of the semicircle depends on the radius of the original circle. Its unit can be expressed in "inches", "feet", "meters" or "centimeters". The perimeter of a semicircle is also known as the circumference of the semicircle.
What is the Formula for Perimeter of Semicircle?
The formula for the perimeter of the semicircle is the sum of the length of the diameter of the original circle and half the circumference of the original circle. Thus, the formula for the perimeter of the semicircle is given as P = (πr + 2r) units where "P" is the perimeter of the semicircle and "r" is the radius of the semicircle.
How to Find the Perimeter of Semicircle?
We can find the perimeter of the semicircle using the following steps:
 Step 1: Find the product of π and r where "r" is the radius of the semicircle.
 Step 2: Find the diameter of the semicircle.
 Step 3: Add the values in Step 1 and Step 2.
 Step 4: The value obtained in Step 3 is the perimeter of the semicircle.
How Do You Find the Radius If Perimeter of Semicircle is Given?
We can determine the radius of the perimeter of the semicircle is given by using the following steps:
 Step 1: Write the given dimensions of the semicircle.
 Step 2: Assume the radius of the semicircle to be "r" units.
 Step 3: Use the formula P = (πr + 2r) units where "P" is the perimeter of the semicircle and "r" is the radius of the semicircle to determine the value of radius.
 Step 4: Once the equation is obtained, solve for "r" to determine the value of the radius of the semicircle.
How to Find the Area of Semicircle When the Circumference of Semicircle is Given?
We can find the area of semicircle when the circumference of the semicircle is given using the following steps:
 Step 1: Find the value of the radius using the formula of the perimeter of the semicircle, P = (πr + 2r), and equate it to the value of the perimeter of the semicircle.
 Step 2: Once, the equation is obtained, solve for "r".
 Step 3: Use the formula, A = (πr^{2})/2 to determine the value of the area of the semicircle.
What Happens to the Circumference of Semicircle If Radius of Semicircle is Doubled?
If the radius of the semicircle is doubled then the perimeter will also get doubled as C = (π + 2)r and the value of radius gets doubled as (2r). Thus, the circumference of semicircle P = (π + 2)(2r) = 2(π + 2)r, which is twice the original circumference.
What is the Formula For the Circumference of Semicircle In Terms of the Diameter of Semicircle?
The formula for the circumference of the semicircle is the C = (πr + 2r). As we know diameter is twice the value of the radius, thus, d = 2r. The formula of the circumference of semicircle becomes, C = π(d/2) + d.