Question

What is the radius of the incircle of the right angled triangle whose sides measure $3,4$ and $5$ units?

• A. $1$ unit
• B. $2$ units
• C. $3$ units
• D. $4$ units

Answer 1

Answer: (A)

$1$ unit

Radius of the incircle $=$ $\frac{2\times \text{area of triangle}}{\text{sum of sides}}$

Area of triangle $=$ $\frac{1}{2}\times 3\times 4$ $=6$

Sum of the sides $=3+4+5=12$

Radius of the incircle $=$ $\frac{2\times 6}{12}$ $=1$ unit