Single correct option
The two shorter sides of a right-angled triangle are 9 cm and 12 cm. What is the radius of its inscribed circle?
- A. 4 cm
- B. 3 cm
- C. 4.5 cm
- D. 2.5 cm
Show answer and solution
Answer: (B) 3 cm
Hypotenuse = √(81 + 144) = √225 = 15 cm.
For a right triangle, inradius r = (a + b − c)/2 = (9 + 12 − 15)/2 = 3 cm.
Check with r = Area/semiperimeter: area = (9 × 12)/2 = 54, s = (9 + 12 + 15)/2 = 18, r = 54/18 = 3. ✓
For a right triangle, inradius r = (a + b − c)/2 = (9 + 12 − 15)/2 = 3 cm.
Check with r = Area/semiperimeter: area = (9 × 12)/2 = 54, s = (9 + 12 + 15)/2 = 18, r = 54/18 = 3. ✓
Saved on this device. Sign in or create a free account to keep it on every device.