Question

If perimeter of triangle is 36cm and two sides are 9and 12cm.
find the area​

Answer 1

Answer:

Area=54²

Step-by-step explanation:

Given=》

a=9cm

b=12cm

c=?

perimeter=36cm

Solution =》

perimeter =a+b+c

36=9+12+c

36=21+c

36-21=c

c=15

Using heron's formula

S=a+b+c/2

s=9+12+15/2

s=36/2

s=18

area =√{s(s - a)(s - b)(s - c) }

area= √s(s−a)(s−b)(s−c)

area= √18(18−15)(18−12)(18−9)

area= √18×3×6×9

area= √6×3×3×6×9

area=3×6×9

Area=54cm²

Answer 2

Step-by-step explanation:

perimeter of triangle =36cm(side+side+side)

two sides of triangle =9cm and 12cm

the third side of triangle =9cm+12cm=21cm

=36cm-21cm= 15cm

area of triangle =s(s-a)(s-b)(s-c)÷2

=9+12+15÷2

=36÷2

=18cm