Question

If the sides of a triangle are 13,14 15, then the radius of its incircle is

• A. $\frac{67}{8}$
• B. $\frac{65}{4}$
• C. 4
• D. 24

Answer 1

Answer: (C)

4

Answer 2

$r = \frac{\Delta}{s}\text{and}s = \frac{a + b + c}{2} = \frac{13 + 14 + 15}{2} = 21$

⇒ $\Delta = \sqrt{21 \times 8 \times 7 \times 6} = 84$ ⇒ $r = \frac{84}{21} = 4$.