Prove that if chords of congruent circles subtend equal angles at their centres,then the chords are equal.

Vedclass pdf generator app on play store
Vedclass iOS app on app store
(N/A) Let there be two congruent circles with centres $O$ and $O'$.
Let $AB$ be a chord of the first circle and $CD$ be a chord of the second circle.
Given that $\angle AOB = \angle CO'D$.
In $\triangle AOB$ and $\triangle CO'D$:
$1$. $OA = O'C$ (Radii of congruent circles are equal).
$2$. $OB = O'D$ (Radii of congruent circles are equal).
$3$. $\angle AOB = \angle CO'D$ (Given).
By $SAS$ (Side-Angle-Side) congruence criterion,$\triangle AOB \cong \triangle CO'D$.
Since the triangles are congruent,their corresponding parts are equal $(CPCT)$.
Therefore,$AB = CD$.
Hence,the chords are equal.

Explore More

Similar Questions

In a circle with centre $P$,$AB$ and $CD$ are equal chords. If $\angle APB = 70^{\circ}$,then find $\angle CPD$. (in $^{\circ}$)

$AB$ is a chord of a circle with centre $P$. Point $C$ is a point other than $A$ and $B$ on the major arc $AB$. If $\angle ACB + \angle APB = 135^{\circ}$,then find $\angle ACB$ and $\angle APB$.

Difficult
View Solution

Prove that the line of centres of two intersecting circles subtends equal angles at the two points of intersection.

If circles are drawn taking two sides of a triangle as diameters,prove that the point of intersection of these circles lies on the third side.

$AC$ and $BD$ are chords of a circle which bisect each other. Prove that $AC$ and $BD$ are diameters.

Difficult
View Solution

Vedclass Products

For Students

Vedclass Test Series

Mock tests in real JEE/NEET style with performance analysis. 5-day free trial.

Start Free Trial
For Teachers

Exam Paper Generator

Generate Set A/B/C/D exam papers from 7.5L+ questions in 2 minutes. 3 chapters free.

Try Free
For Institutes

Online Exam Module

Live online exams with unlimited students, 360° analytics & white-label branding.

See Demo