Show:
Vocabulary
Circumference
Perimeter of a Semi Circle
Area of a Circle
Perimeter and Area of Composite Figures
100
What is the circumference?
length around a circle
100
How do you find the circumference if I give you the diameter?
C= D x Pi
100
How do you find the perimeter of a semi-circle?
Find the curve: Circumference / 2 Add the bottom to close the figure: + Diameter Perimeter = C/2 + D
100
How do you find the area of a circle?
A = r to the power of 2 x pi
100
How do you find the perimeter of a composite figure?
Add all of the sides.
200
What is the radius?
Any point from the outside of a circle to the center
200
How do you find the Circumference if I give you the radius?
C = (R x 2) x Pi
200
The diameter of the semi- circle is 12, what is the perimeter?
Perimeter= C/2 +D (12 x 3.14) / 2 + 12 = 37.68 / 2 + 12 = 18.84 + 12 = 30.84
200
Find the area if the radius is 3 mm.
A= 28.26 mm
200
How do you find the curve of a semi-circle when you need to add it as a side? Do you add the diameter?
You divide the circumference by 2. No you do not add the diameter if it is inside the shape because the perimeter is only the outside of the shape.
300
What is the Diameter?
Point from one side of a circle that connects to another point on the circle and passes through the center
300
Diameter is 5 m ... find the circumference.
C= 15.7m
300
What do you do to find the perimeter of a semi circle if the radius is what you are given?
Find the circumference with the radius, then divide by 2, and add the diameter.
300
How do you find the area of a circle if I give you the diameter?
Divide the diameter by 2 to get the radius and then square it and multiply by Pi.
300
How do you find the area of a composite figure?
Divide the figure into known shapes and then find the areas of them and then add them together.
400
What is a semi-circle?
Half of a circle.
400
The Radius is 5 mi ... what is the circumference?
C= 31.3 mi
400
The radius of the semi-circle is 7 km. What is the perimeter?
Perimeter = (R x 2) x Pi / 2 + D (7 x 2) x 3.14 / 2 + 14= 14 x 3.14 /2 + 14= 43.96/ 2 +14= 21.98 + 14= 35.98 km
400
The Diameter is 10 yd , find the area.
A = 78.5 yd
400
Find the perimeter of the composite figure that I draw.
Answer will be given on board.
500
What is Pi?
Shortened it is 3.14, but it represents the ratio of the circumference to the diameter.
500
If the problem gives you the circumference, what can you do to give me the diameter and radius?
Diameter- divide by 3.14 Radius- Divide by 3.14 and then by 2
500
Could you actually simplify the process of finding the perimeter with the radius?
Yes, Since you already have the radius you do not need to multiply by 2 and then divide by two after multiplying by pi. You could just multiply the radius by pi and then add the denominator and you have the perimeter of the semi-circle.
500
How do you find the area of a semi-circle?
Find the area of the circle and divide by 2... pay attention to whether they give you the radius or the diameter.
500
Find the area of the composite figure I draw.
Answer will be given on the board.