In $\Delta ABC$,$A-D-B$,$A-E-C$ and $BD = CE$. If $m\angle B = m\angle C$,prove that $\overline{DE} \parallel \overline{BC}$.

Vedclass pdf generator app on play store
Vedclass iOS app on app store
(N/A) Given: In $\Delta ABC$,$A-D-B$,$A-E-C$,$BD = CE$,and $m\angle B = m\angle C$.
Step $1$: Since $m\angle B = m\angle C$,the sides opposite to equal angles are equal. Therefore,$AB = AC$.
Step $2$: We can express the sides as $AB = AD + DB$ and $AC = AE + EC$ (since $A-D-B$ and $A-E-C$).
Step $3$: Substituting these into $AB = AC$,we get $AD + DB = AE + EC$.
Step $4$: Since $BD = CE$,we can substitute $CE$ with $BD$ in the equation: $AD + DB = AE + DB$.
Step $5$: Subtracting $DB$ from both sides,we get $AD = AE$.
Step $6$: Now,consider the ratios $\frac{AD}{DB}$ and $\frac{AE}{EC}$. Since $AD = AE$ and $DB = EC$,it follows that $\frac{AD}{DB} = \frac{AE}{EC}$.
Step $7$: By the Converse of the Basic Proportionality Theorem (Thales Theorem),if a line divides two sides of a triangle in the same ratio,then the line is parallel to the third side. Therefore,$\overline{DE} \parallel \overline{BC}$.

Explore More

Similar Questions

In $\Delta PQR$,$m \angle Q = 90^{\circ}$ and $\overline{QM}$ is an altitude. If $QM = 6$ and $MR = 9$,then $PR = \ldots$

In $\Delta ABC$ and $\Delta PQR$,$\angle A \cong \angle P$ and $\angle B \cong \angle R$. Then,the correspondence $ABC \leftrightarrow \ldots$ is a similarity.

In $\Delta PQR$,$M$ and $N$ are the midpoints of $\overline{PQ}$ and $\overline{PR}$ respectively. If the area of $\Delta PMN$ is $24$,find the area of $\Delta PQR$.

In $\Delta XYZ$,the bisector of $\angle X$ intersects $\overline{YZ}$ at $M$. If $XY = 6$,$XZ = 8$ and $YM = 4.2$,find $YZ$.

In rhombus $ABCD$,$AC = 12$ and $BD = 16$. Find the perimeter of rhombus $ABCD$.

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