Question

ABC is a right angled triangle, AB = 3cm, BC = 5 cm and AC = 4cm, then the inradius of the circle is:

• A. 1 cm
• B. 1.25 cm
• C. 1.5 cm
• D. None of these

Answer 1

The correct option is A 1 cm

Inradius of an incircle of right angled triangle
$=\frac{Base+Altitude-Hypotenuse}{2}=\frac{4+3-5}{2}=1cm$

Alternatively :
$Inradius=\frac{Areaoftriangle}{Simiperimeteroftriangle}=\frac{\frac{(3\times 4)}{2}}{\frac{(3+4+5)}{2}}=\frac{6}{6}=1cm$