1. Semicircle application

2. Question 1: If the circumference of the semicircle is 180cm what will be the area of the semicircle. Solution: Given: P = 180cm To find: area of semicircle To find area we will need radius, since perimeter is given, lets find radius using the perimeter formula
To find radius of semi circle
P = r(π + 2)
Area of semi circle
A =
= 11 x 5 x 35
Area = cm (Ans) 11 5 5 30 6
r = 5 x 7 = 35cm

3. Question 2: Perimeter of semicircle is 324cm. Find its radius.
Arc length of semi-circle = r(π + 2)
324 = r(π + 2) 9 54 6
r = 9 x 7 = 63cm (ans)

4. Question 3: Perimeter of semicircle is 144m. Find its diameter.
144cm
Arc length of semi-circle = r(π + 2)
144 = r(π + 2) 4 24 6
r = 4 x 7 = 28m
d = 2 x r = 2 x 28 = 56 m (ans)

5. A B C Question 4: Calculate perimeter of the shape below 12.57cm 4cm
Semi-circle of diameter = 8cm A
Semi-circle of diameter = 4cm
4cm
Semi-circle of diameter = 4cm
4cm
4cm B C
6.29cm
6.29cm
Perimeter of combined Shapes= Perimeter of A + Perimeter of B + Perimeter of C
Arc length of semi-circle A =
Arc length of semi-circle B or C =
=12.57cm
=6.29cm
Perimeter of combined Shapes= 12.57cm cm cm = 25.15cm

6. Recap A semicircle is half part of a circle
Perimeter of a semicircle = r(π + 2)
Area of a semicircle =

7. Try these
Find the perimeter and area of a semi circle whose radius is 21 cm.
Find the area of the semicircle whose circumference is 108cm