In trapezium $ABCD$,$AB \parallel CD$ and $E$ is the midpoint of $AD$. $A$ line drawn through $E$ and parallel to $AB$ intersects $BC$ at $F$. Prove that $F$ is the midpoint of $BC$ and $EF = \frac{1}{2}(AB + CD)$.

Vedclass pdf generator app on play store
Vedclass iOS app on app store
(A) $1$. Join $AC$. Let $AC$ intersect $EF$ at point $G$.
$2$. In $\triangle ADC$,$E$ is the midpoint of $AD$ and $EG \parallel DC$ (since $EF \parallel AB$ and $AB \parallel CD$). By the Converse of the Midpoint Theorem,$G$ is the midpoint of $AC$. Thus,$EG = \frac{1}{2}CD$.
$3$. In $\triangle ABC$,$G$ is the midpoint of $AC$ and $GF \parallel AB$. By the Converse of the Midpoint Theorem,$F$ is the midpoint of $BC$. Thus,$GF = \frac{1}{2}AB$.
$4$. Adding the two segments: $EF = EG + GF = \frac{1}{2}CD + \frac{1}{2}AB = \frac{1}{2}(AB + CD)$.
$5$. Hence,$F$ is the midpoint of $BC$ and $EF = \frac{1}{2}(AB + CD)$.

Explore More

Similar Questions

$ABCD$ is a parallelogram and $P$ and $Q$ are points on the diagonal $AC$ such that $AP = PQ = QC$. Prove that $BQ \parallel DP$ and $BD$ bisects $PQ$.

In $\Delta ABC$,$P, Q,$ and $R$ are the midpoints of $AB, BC,$ and $CA$ respectively. Prove that $PBQR, PQCR,$ and $PQRA$ all are parallelograms.

The angle between two altitudes of a parallelogram drawn from the vertex of an obtuse angle is $60^{\circ}$. Find the angles of the parallelogram.

In a rhombus $ABCD$,$\angle B = 80^{\circ}$,then $\angle ADB = \ldots$ (in $^{\circ}$)

Prove that the line segment joining the midpoints of the diagonals of a trapezium is parallel to the parallel sides of the trapezium and is equal to half the difference of the lengths of the parallel sides.

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