Chapter 10, Problem 25RP

To determine

To find : Circumference of the circle to the nearest cm.

Answer to Problem 25RP

  $1257.48$ cm

Explanation of Solution

Given information :

The given information is Length of chord = $80$ cm, Distance of the chord AB from centre O, OX = $9$ cm.

  

Formula Used:

Circumference of circle = $2\pi r$

Calculation :

  $\begin{array}{l}OX\perp AB\\ \therefore AX=BX=\frac{1}{2}AB=40cm\\ \therefore O{B}^2=O{X}^2+B{X}^2\\ =81+1600\\ O{B}^2=1681\\ OB=\sqrt{1681}=41\text{ cm}\end{array}$

Circumference of circle = $2\times \pi \times OB$

  $\begin{array}{l}=2\times 3.14\times 41\\ =257.48cm\end{array}$