MCQ 11 Mark
If $A B=12 cm, B C=16 cm$ and $A B$ is perpendicular to $B C$, then the radius of the circle passing through the points A, B and C is


- A6 cm
- B8 cm
- ✓10 cm
- D12 cm
Answer
View full question & answer→Correct option: C.
10 cm
(c) 10 cm
Perpendicular from the centre to a chord bisects the chord. Therefore, $L$ and $M$ are mid-points of $A B$ and $B C$ respectively. Thus, in right triangle $O L B$, we have
$O L=B M=\frac{1}{2} B C=8 cm \text { and } B L=\frac{1}{2} A B=6 cm$
Applying Pythagoras theorem in $\triangle O L B$, we obtain
$O B^2=O L^2+L B^2 \Rightarrow O B=\sqrt{8^2+6^2}=\sqrt{100}=10 cm$
Perpendicular from the centre to a chord bisects the chord. Therefore, $L$ and $M$ are mid-points of $A B$ and $B C$ respectively. Thus, in right triangle $O L B$, we have
$O L=B M=\frac{1}{2} B C=8 cm \text { and } B L=\frac{1}{2} A B=6 cm$
Applying Pythagoras theorem in $\triangle O L B$, we obtain
$O B^2=O L^2+L B^2 \Rightarrow O B=\sqrt{8^2+6^2}=\sqrt{100}=10 cm$

























