Question

Let a, b, c be sides of triangle
[
begin{array}{c}
text { Perincter }=42=a+b+c
qquad begin{aligned}
42 &=18+10+c
c &=42-28
c &=14 text { cin }
s=frac{4+b+c}{2}=frac{42}{2}=21
end{aligned}
end{array}
]
Now by heron's formnla
Aua ( =sqrt{5(5-a)(5-b)(5-c)} )
[
begin{aligned}
&=sqrt{21(21-18)left(21^{2}-10right)(21-14)}
&=sqrt{21 times 3 times 11 times 7}=sqrt{21 times 21 times 11}
text { Area } &=21 sqrt{11} mathrm{cm}^{2}
end{aligned}
]

# | Find area op triangle two sides of | which are 18 cm and loom and i perimeter is 42cm.

Solution