Question
Answer: Option D
:
D
We are given two triangles ABC and PQR such that △ABC∼△PQR.
For finding the areas of the two triangles, we draw altitudes AM and PN of the triangles ABC and PQR respectively, as shown below.
Now,
area of△ABC=12×BC×AMandarea of△PQR=12×QR×PN
So,
areaof△ABCareaof△PQR=12×BC×AM12×QR×PN=BC×AMQR×PN⋯(1)
Now, in â–³ABM andâ–³PQN,
∠B=∠Q (As△ABC∼△PQR)
and∠AMB=∠PNQ=90∘.
So, △ABM∼△PQN
( By AA similarity criterion)
∴AMPN=ABPQ⋯(2)
Also, △ABC∼△PQR (Given)
So, ABPQ=ACPR=BCQR⋯(3)
From (1) and (3), we get,
areaof(ABC)areaof(PQR)=AB×AMPQ×PN=AB×ABPQ×PQ=AB2PQ2
Now using (3), we get,
areaofâ–³ABCareaofâ–³PQR=AB2PQ2=BC2QR2=AC2PR2
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:
D
We are given two triangles ABC and PQR such that △ABC∼△PQR.
For finding the areas of the two triangles, we draw altitudes AM and PN of the triangles ABC and PQR respectively, as shown below.
Now,
area of△ABC=12×BC×AMandarea of△PQR=12×QR×PN
So,
areaof△ABCareaof△PQR=12×BC×AM12×QR×PN=BC×AMQR×PN⋯(1)
Now, in â–³ABM andâ–³PQN,
∠B=∠Q (As△ABC∼△PQR)
and∠AMB=∠PNQ=90∘.
So, △ABM∼△PQN
( By AA similarity criterion)
∴AMPN=ABPQ⋯(2)
Also, △ABC∼△PQR (Given)
So, ABPQ=ACPR=BCQR⋯(3)
From (1) and (3), we get,
areaof(ABC)areaof(PQR)=AB×AMPQ×PN=AB×ABPQ×PQ=AB2PQ2
Now using (3), we get,
areaofâ–³ABCareaofâ–³PQR=AB2PQ2=BC2QR2=AC2PR2
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