Question

In the figure to the right, if AC = 21 and BC = 18, what is theradius?А.BDсThe radius is approximately(Round to the nearest tenth as needed.)

Answer 1

We are to find the radius of the circle and it is obvious that the radius (AB) is the third side of the righht angle.

By Pythagoras' theorem;

`\begin{gathered} AC^2=AB^2+BC^2 \\ 21^2=AB^2+18^2 \\ AB^2=21^2-18^2 \\ AB^2\text{ = 441 - 324} \\ AB^2\text{ = 117} \\ AB\text{ = }\sqrt[]{117}\text{ = 10.8167} \\ AB\text{ = 10.8 (nearest tenth)} \end{gathered}`

The radius of the circle is approximately 10.8 units to the nearest tenth.