Question

In $\Delta$ $ABC$ the sides opposite to angles $A,B,C$ are denoted by $a,b,c$ respectively, If $a=13,b=14,c=15,$ then $r=?$

• A. $4$
• B. $8$
• C. $2$
• D. $6$

Answer 1

The correct option is A $4$

as we know that $△=\sqrt{s(s-a)(s-b)(s-c)}$

and $s=\frac{13+14+15}{2}=21$

$\Rightarrow △=\sqrt{21\ast 8\ast 7\ast 6}=84$

and we know that

$△=rs\Rightarrow 84=r\ast 21\Rightarrow r=4$

Therefore, Answer is $A$