Mathematics
Finding Circumference of a circle
Question :Find the circumference of a circle if its radius is 14,take(π=22/7)
Solution
C=2πr
C=2x22/7x14
=2x22/7x14
=88cm
Finding the diameter or radius given the circumference of a circle.
A)Find the diameter of a circle if its circumference is 44cm. take(π=22/7)
Solution
Circumference of circle= πd(formula)
44=22/7xd
=d=44x7/22
=14cm
B)Find the radius of a circle if its circumference is 300cm,correct to 2 decimal places. take(π=3.142)
Solution
Circumference of a circle=2πr(formula)
300=2x3.142xr
R=300/2x3.142
=47.74cm(2d.p.)
Solving problem involving circumference of circles
Example:A wheel of a car has radius of 28cm.if it makes one full turn, find the distance covered. take(π=22/7)
Solution
Understand:radius of the wheel=28cm
=one full turn is the circumference of the wheel .
=Find the distance the wheel covered ,that is,its circumference .
Plan:circumference of circle=2πr
Solve:circumference of circle=2 πr
2x22/7x28
=176cm
Check:
2x22/7xr
R=176x1/2x7/22
=28cm
