Prove that the sum of the squares of the sides of a rhombus is equal to the sum of the squares of its diagonals.

Vedclass pdf generator app on play store
Vedclass iOS app on app store
(N/A) Let $ABCD$ be a rhombus with diagonals $AC$ and $BD$ intersecting at $O$.
In $\Delta AOB, \Delta BOC, \Delta COD,$ and $\Delta AOD,$
Applying the Pythagoras theorem,we obtain:
$AB^2 = AO^2 + OB^2$ $...(1)$
$BC^2 = BO^2 + OC^2$ $...(2)$
$CD^2 = CO^2 + OD^2$ $...(3)$
$AD^2 = AO^2 + OD^2$ $...(4)$
Adding all these equations,we obtain:
$AB^2 + BC^2 + CD^2 + AD^2 = 2(AO^2 + OB^2 + OC^2 + OD^2)$
Since the diagonals of a rhombus bisect each other at right angles,$AO = OC = AC/2$ and $BO = OD = BD/2$.
Substituting these values:
$= 2((AC/2)^2 + (BD/2)^2 + (AC/2)^2 + (BD/2)^2)$
$= 2(2(AC/2)^2 + 2(BD/2)^2)$
$= 2(AC^2/2 + BD^2/2)$
$= AC^2 + BD^2$
Thus,the sum of the squares of the sides of a rhombus is equal to the sum of the squares of its diagonals.

Explore More

Similar Questions

In $\Delta ABC$,$m \angle B = 90^{\circ}$ and $\overline{BM}$ is an altitude to the hypotenuse $\overline{AC}$. If $BM = 10$ and $CM = 5$,find the perimeter of $\Delta ABC$.

In $\Delta ABC$,$A-M-B$,$A-N-C$ and $\overline{MN} \parallel \overline{BC}$. If $AM = 6$,$MB = 12$ and $AN = 8$,find $AC$.

In the given figure,if $PQRS$ is a parallelogram and $AB \parallel PS$,then prove that $OC \parallel SR$.

Difficult
View Solution

In $\Delta ABC$,the bisector of $\angle A$ intersects $\overline{BC}$ at $D$. If $AB = 5.2$,$AC = 10.4$,and $BD = 3.8$,find $BC$.

In $\Delta PQR$,$m \angle Q = 90^\circ$. If $PQ : QR = 1 : 1$,then $PQ : PR = \ldots$

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