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Byju's Answer
Standard VII
Mathematics
Equal Angles Subtend Equal Sides
if triangle A...
Question
if triangle ABC is similar to the triangle QRP, ar(ABC)/ar(PQR)= 9/4, AB=18 cm BC=15 cm, then PR= ?
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Solution
Given :
A
r
e
a
o
f
∆
A
B
C
A
r
e
a
o
f
∆
Q
R
P
=
9
4
AB = 18 cm , BC = 15 cm So PR = ?
We know when two triangles are similar then " The areas of two similar triangles are proportional to the squares of their corresponding sides.
A
r
e
a
o
f
∆
A
B
C
A
r
e
a
o
f
∆
Q
R
P
=
A
B
2
Q
R
2
=
B
C
2
P
R
2
=
A
C
2
Q
P
2
So , we take
A
r
e
a
o
f
∆
A
B
C
A
r
e
a
o
f
∆
Q
R
P
=
B
C
2
P
R
2
Now substitute all given values and get
9
4
=
15
2
P
R
2
Taking square root on both hand side , we get
3
2
=
15
P
R
PR = 10 cm
Suggest Corrections
2
Similar questions
Q.
If
△
A
B
C
∼
△
Q
R
P
,
A
r
(
A
B
C
)
A
r
(
Q
R
P
)
=
9
4
,
A
B
=
18
c
m
and
B
C
=
15
c
m
; then
P
R
is equal to:
Q.
If
△
A
B
C
∼
△
P
Q
R
,
a
r
(
A
B
C
)
a
r
(
P
Q
R
)
=
9
4
,
A
B
=
18
c
m
and
B
C
=
15
c
m
, then
Q
R
is equal to:
Q.
If
△
A
B
C
∼
△
Q
R
P
,
a
r
(
△
A
B
C
)
a
r
(
△
Q
R
P
)
=
9
4
, and
B
C
=
15
c
m
, then find
P
R
.
Q.
If
Δ
A
B
C
∼
Δ
Q
R
P
,
a
n
(
Δ
A
B
C
Δ
Q
R
P
)
=
9
4
A
B
=
9
4
,
A
B
=
18
,
and
B
C
=
15
c
m
then find the length (in cm) of
P
R
?
Q.
△
P
Q
R
∼
△
A
B
C
,
P
Q
=
4
c
m
,
Q
R
=
6
c
m
and
P
R
=
5
c
m
. If
A
B
=
8
c
m
then find the perimeter of
△
A
B
C
.
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