Let P,Q, R be the mid points of the sides BC, CA and AB of a given ∆ABC. Let BQ and PR
meet at X and CR and PQ meet at Y. Show that
a) XY║BC
Answers
Step-by-step explanation:n a triangle line joining mid - point of two sides are parallel and half of third side
PQ∥AB
PQ=
2
1
AB→(i)
QR∥BC
QR=
2
1
BC→(ii)
PR∥AC
PQ=
2
1
AC→(iii)
fromequation(i)(ii)
two pairs are parallel so, BPQR is a parallelogram
BP=QR=
2
BC
→(iv)
In parallelogram diagonals bisects each other so
X is mid -point to PR. Similarly,
Y is mid- point on QP InΔRPQ
InΔRPQ
XY=
2
1
QR
XY=
2
1
(
2
1
BC)
4
1
BC
Given
ABC is a Triangle.
P is the m.p of BC
Q is the m.p of CA
R is the m.p of AB
To prove
XY =  BC
Proof
In ΔABC
R is the midpoint of AB.
Q is the midpoint of AC.
∴ By Midpoint Theorem,
RQ║BC
RQ║BP → 1 [Parts of Parallel lines]
RQ =  BC → 2
Since P is the midpoint of BC,
RQ = BP → 3
From 1 and 3,
BPQR is a Parallelogram.
BQ and PR intersect at X
Similarly,
PCQR is a Parallelogram.
PQ and CR intersect at Y.
 X and Y are Midpoints of sides PR and PQ respectively.
In ΔPQR
X is the midpoint of PR
Y is the midpoint of PQ
∴ By Midpoint Theorem,
XY =  RQ
From 3,
XY =  +  BC
XY =  BC
Step-by-step explanation:
I hope it helps you
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