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Byju's Answer
Standard IX
Mathematics
Area of Any Polygon - by Heron's Formula
Find the area...
Question
Find the area of a triangle two sides of which are
18
c
m
and
10
c
m
and the perimeter is
42
c
m
.
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Solution
Two sides length are given, we need to figure out the length of this side.
⇒
Let
x
be length of third side
⇒
Perimeter
=
42
c
m
⇒
18
+
10
+
x
=
42
⇒
x
=
42
−
28
=
14
c
m
⇒
2
s
=
42
⇒
s
=
21
c
m
⇒
a
=
18
,
b
=
10
,
c
=
14
⇒
A
=
√
s
(
s
−
a
)
(
s
−
b
)
(
s
−
c
)
⇒
√
21
(
21
−
18
)
(
21
−
10
)
(
21
−
14
)
=
√
21
×
3
×
11
×
7
⇒
A
=
21
√
11
c
m
2
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11
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Area of Any Polygon - by Heron's Formula
Standard IX Mathematics
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