Question

find the area of a triangle, whose sides are 18 cm and 10 cm and perimeter 42 CM
a) 21√11cm²
b)11√21cm²
c)2√11cm²
d) None of these​

Answer 1

Answer:

21√11cm²

Step-by-step explanation:

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

Hope it helps  :)

Answer 2

Step-by-step explanation:

this is your questions answer