Problems 1.2. Calculate (a) the circumference of a circle of radius 3.5cm and (b) area of a circlue of radius 4.65cm
Solution: Data: r = 3.5cm, A = 4.65cm.
(a) Circumference of a circle is given by the formula:
S = 2Ï€r = 2 x 3.142 x 3.5 = 21.994
The least number of significant figures is 2, so we should round off the answer to 2:
S = 22cm Ans
(b) Area of circle is given by:
A = 7Ï€r² = 3.142 x (4.65)² = 3.142 x 21.6225 = 67.9564
The least number of significant figures is 3, so we should round off the answer to 3:
A = 67.9cm² Ans
