Prove that a diagonal of a parallelogram divides it into two congruent triangles.

Vedclass pdf generator app on play store
Vedclass iOS app on app store
(N/A) Let $ABCD$ be a parallelogram and $AC$ be a diagonal. Observe that the diagonal $AC$ divides parallelogram $ABCD$ into two triangles,namely,$\Delta ABC$ and $\Delta CDA$. We need to prove that these triangles are congruent.
In $\Delta ABC$ and $\Delta CDA$,note that $BC \parallel AD$ and $AC$ is a transversal.
So,$\angle BCA = \angle DAC$ (Pair of alternate interior angles).
Also,$AB \parallel DC$ and $AC$ is a transversal.
So,$\angle BAC = \angle DCA$ (Pair of alternate interior angles).
And $AC = CA$ (Common side).
Therefore,$\Delta ABC \cong \Delta CDA$ (by $ASA$ congruence rule).
Thus,the diagonal $AC$ divides the parallelogram $ABCD$ into two congruent triangles $ABC$ and $CDA$.

Explore More

Similar Questions

In a quadrilateral $ABCD$,$\angle A : \angle B : \angle C : \angle D = 4 : 5 : 4 : 5$. Find the measure of each angle of the quadrilateral and state the type of quadrilateral $ABCD$.

Can all the four angles of a quadrilateral be obtuse angles? Give reason for your answer.

In $\Delta XYZ$,$A$ and $B$ are the midpoints of $XY$ and $XZ$ respectively. If $AB = 7.5 \, cm$,then find the length of $YZ$ in $cm$.

$D$ and $E$ are the mid-points of the sides $AB$ and $AC$ respectively of $\triangle ABC$. $DE$ is produced to $F$. To prove that $CF$ is equal and parallel to $DA$,we need an additional information which is

$P$ is the mid-point of the side $CD$ of a parallelogram $ABCD$. $A$ line through $C$ parallel to $PA$ intersects $AB$ at $Q$ and $DA$ produced at $R$. Prove that $DA = AR$ and $CQ = QR$.

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