Chapter 12.2, Problem 29HP

To determine

To find : Label length of the radius and state the area of circle to nearest tenth.

Answer to Problem 29HP

Radius = $16.05$ cm, Area = $809.3$ cm²

  

Explanation of Solution

Given information :

The given information is, Two area $800$ sq.cms. and $820$ sq.cms. of circles.

Formula Used:

Area = $\pi r^2$ , $r$ is radius of circle.

Calculation :

  

Area between $\text{800}$ cm² and $\text{820}$ cm². Let $\text{810}$ cm².

  $\begin{array}{l}A=\pi r^2\\ \Rightarrow 810=\pi r^2\\ \Rightarrow r^2=\frac{810}{\pi }\\ \Rightarrow r^2=257.831\\ \Rightarrow r=16.05cm\\ \therefore Area,A=\pi r^2\\ $ \Rightarrow A=\pi {(16.05)}^2$\Rightarrow A=809.8c{m}^2\end{array}$

Nearest tenth of $\text{809}\text{.28}$ cm² is $\text{809}\text{.3}$ cm².