Question

If R is the radius of circumcircle of $\Delta$ ABC, then
$R=\frac{abc}{4S}$

• A. True
• B. False

Answer 1

The correct option is A True

Let $a=2RsinA=2R.2sin\frac{A}{2}cos\frac{A}{2}$

or $a=2R.$ $\frac{2}{bc}\sqrt{s(s-a)(s-b)(s-c)}=\frac{4RS}{bc}$

$\therefore R=\frac{abc}{4S}.$ where $S=$area of triangle