Write 'True' or 'False' and give reasons for your answer.
If a chord $AB$ subtends an angle of $60^{\circ}$ at the centre of a circle,then the angle between the tangents at $A$ and $B$ is also $60^{\circ}$.

Vedclass pdf generator app on play store
Vedclass iOS app on app store
(B) False
Given that a chord $AB$ subtends an angle of $60^{\circ}$ at the centre $O$ of a circle.
i.e.,$\angle AOB = 60^{\circ}$.
Since $OA = OB$ (radii of the same circle),$\triangle OAB$ is an isosceles triangle.
Therefore,$\angle OAB = \angle OBA = (180^{\circ} - 60^{\circ}) / 2 = 60^{\circ}$.
Let the tangents at points $A$ and $B$ intersect at point $C$.
We know that the radius is perpendicular to the tangent at the point of contact.
So,$OA \perp AC$ and $OB \perp BC$.
Therefore,$\angle OAC = 90^{\circ}$ and $\angle OBC = 90^{\circ}$.
Now,$\angle BAC = \angle OAC - \angle OAB = 90^{\circ} - 60^{\circ} = 30^{\circ}$.
Similarly,$\angle ABC = \angle OBC - \angle OBA = 90^{\circ} - 60^{\circ} = 30^{\circ}$.
In $\triangle ABC$,the sum of interior angles is $180^{\circ}$.
So,$\angle ACB + \angle BAC + \angle ABC = 180^{\circ}$.
$\angle ACB + 30^{\circ} + 30^{\circ} = 180^{\circ}$.
$\angle ACB = 180^{\circ} - 60^{\circ} = 120^{\circ}$.
Thus,the angle between the tangents is $120^{\circ}$,not $60^{\circ}$.

Explore More

Similar Questions

$\odot(O, 41)$ and $\odot(O, 9)$ are concentric circles. The chord $\overline{AB}$ of $\odot(O, 41)$ touches $\odot(O, 9)$ at point $M$. Then $AB = \ldots$

Difficult
View Solution

$AB$ is a diameter and $AC$ is a chord of a circle with centre $O$ such that $\angle BAC = 30^{\circ}$. The tangent at $C$ intersects the extended $AB$ at a point $D$. Prove that $BC = BD$.

$\overline{PA}$ is a tangent to $\odot(O, r)$ drawn from a point $P$ outside a circle. If $m\angle AOP = 40^\circ$,then $m\angle OPA = \ldots$ (in $^\circ$)

In the figure,$O$ is the centre of a circle of radius $5 \, cm$. $T$ is a point such that $OT = 13 \, cm$ and $OT$ intersects the circle at $E$. If $AB$ is the tangent to the circle at $E$,find the length of $AB$ in $cm$.

Difficult
View Solution

$P$ is in the exterior of $\odot (O, 9)$. $A$ tangent from $P$ touches the circle at $T$. If $PT = 40$,then $OP = \ldots$

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