Question

In $\Delta ABC,\angle A=\frac{\pi }{2},b=4,c=3$, then the value of $\frac{R}{r}$ is equal to

• A. $\frac{5}{2}$
• B. $\frac{7}{2}$
• C. $\frac{9}{2}$
• D. $\frac{35}{24}$

Answer 1

The correct option is A $\frac{5}{2}$

As $\Delta ABC$ is right-angled at A, $a=\sqrt{3^2+4^2}=5$
$\Rightarrow \Delta =6$ and $s=6$
$R=\frac{3\times 4\times 5}{4\times 6}=\frac{5}{2}$
$r=\frac{6}{6}=1$
$\therefore \frac{R}{r}=\frac{5}{2}$