Question

find the area of the triangle the sides of which are 15 cm and 10 cm and perimeter =42cm​

Answer 1

Given,
Side a=18cm
Side b=10cm
Perimeter=42cm=a+b+c
:. Putting value
42=18+10+c
42=28+c
42-28=c
14=c
Now,
S=(a+b+c)/2
:. Putting value
S=42/2
S=21
Now according to Heron's formula-
Area of a triangle
=√{s(s-a)(s-b)(s-c)}
:. Putting value
=√{21(21-18)(21-10)(21-14)}
=√{21(3)(11)(7)}
=√4851
=21√11cm²
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Answer 2

Answer:

Given,

Side a=18cm

Side b=10cm

Perimeter=42cm=a+b+c

:. Putting value

42=18+10+c

42=28+c

42-28=c

14=c

Now,

S=(a+b+c)/2

:. Putting value

S=42/2

S=21

Now according to Heron's formula-

Area of a triangle

=√{s(s-a)(s-b)(s-c)}

:. Putting value

=√{21(21-18)(21-10)(21-14)}

=√{21(3)(11)(7)}

=√4851

=21√11cm²

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Step-by-step explanation: