The image of an object placed at a point $A$ before a plane mirror $LM$ is seen at the point $B$ by an observer at $D$ as shown in the figure. Prove that the image is as far behind the mirror as the object is in front of the mirror.

Vedclass pdf generator app on play store
Vedclass iOS app on app store
(N/A) Let $AB$ intersect $LM$ at $O$. We have to prove that $AO = BO$.
Now,$\angle i = \angle r$ ... $(1)$
[$\because$ Angle of incidence = Angle of reflection]
$\angle B = \angle i$ [Corresponding angles] ... $(2)$
And $\angle A = \angle r$ [Alternate interior angles] ... $(3)$
From $(1)$,$(2)$ and $(3)$,we get $\angle B = \angle A$.
In $\triangle BOC$ and $\triangle AOC$,we have:
$\angle 1 = \angle 2 = 90^{\circ}$ [Given]
$OC = OC$ [Common side]
$\angle B = \angle A$ [Proved above]
Therefore,$\triangle BOC \cong \triangle AOC$ [$AAS$ congruence rule].
Hence,$AO = BO$ [$CPCT$].

Explore More

Similar Questions

$\angle ABD$ and $\angle ACE$ are exterior angles of $\Delta ABC$. If $\angle ABD > \angle ACE$,then prove that $AC > AB$.

Measure of each exterior angle of an equilateral triangle is $\ldots \ldots \ldots$ (in $^{\circ}$)

In $\Delta ABC$,$AD$ is a median. Prove that $AB + AC > 2AD$.

In the figure,$ABC$ is a right triangle,right-angled at $B$,such that $\angle BCA = 2 \angle BAC$. Show that the hypotenuse $AC = 2 BC$.

Difficult
View Solution

In the given figure,$AM$ and $BN$ are both perpendicular to $AB$. $MN$ intersects $AB$ at $P$. Also,$P$ is the midpoint of $AB$. Prove that $AM = BN$ and $P$ is the midpoint of $MN$.

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