circle problem 1:
A circle has a radius of 9 cm.
a) calculate the diameter
b) calculate the the perimeter/circumference of the circle.
c) calculate the area of the circle
a) answer diameter
d = 2 * r
d = 2 * 9
d = 18 cm
A: The diameter of the circle is 18 centimeter.
b) answer perimeter
P = d * π
P = 18 * π (π = 3.1415..)
P = 56.55 cm
A: The perimeter of the circle is 56.55 cm.
c) answer area
A = r² * π
A = 9² * π
A = 254.47 cm²
A: The area of the circle is 254.47 square centimeters.
circle problem 2:
A circle has a diameter of 16 cm.
a) Calculate the radius
b) Calculate the the perimeter/circumference of the circle.
c) Calculate the area of the circle
a) answer radius
r = d : 2
r = 16 : 2
r = 8 cm
A: The radius of the circle is 8 centimeter.
b) answer perimeter
P = d * π
P = 16 * π (π = 3.1415..)
P = 50.27 cm
A: The perimeter of the circle is 50.27 cm.
c) answer area
A = r² * π
A = 8² * π
A = 201.06 cm²
A: The area of the circle is 201.06 square centimeters.
circle problem 3:
A circle has a perimeter of 80.3 inches.
a) Calculate the diameter of the circle.
b) Calculate the radius of the circle.
c) Calculate the area of the circle
a) answer diameter
P = d * π (π = 3.1415..)
80.3 = d * π / : π
d = 25.56 inches
A: The diameter of the circle is 25.56 inches.
b) answer radius
r = d : 2
r = 25,56 : 2
r = 12.78 inches
A: The radius of the circle is 12.78 inches.
c) answer area
A = r² * π
A = 12.78² * π
A = 513.11 in²
circle problem 4:
A circle has an area of 140.2 square meters.
a) calculate the radius of the circle
b) calculate the the diameter of the circle.
c) calculate the perimeter of the circle
a) answer radius
A = r² * π (π = 3.1415..)
140.2 = r² * π / : π
44.627…. = r² / √
r = 6.68 meters
A: The radius of the circle is 6.68 meters
b) answer diameter
d = 2 * r
d = 2 * 6.68
d = 13.36 meters
A: The diameter of the circle is 13.36 meters.
c) answer perimeter
P = d * π
P = 13.36 * π
P = 41.97 meters
A: The perimeter of the circle is 41.97 meters.
circle problem 5:
The wheel of a wheel loader has a diameter of 6,02 m.
If the wheel rotates once, how much distance does the wheel loader move?
answer:
The perimeter of the wheel is equal to the distance if the wheel rotates once.
P = d * π
P = 6,02 * π (π = 3.1415..)
P = 18,91 meters
A: The distance the wheel moves is 18,91 meters.