Question

Topic: Heron's formula
22. Find the area of triangle two of whose sides are 18 cm and 10 cm and the perimeter is 42 cm​

Answer 1

A+B+C=perimeter

18+10+c=42

c+28=42

c=42-28

c=14cm

S=p/2

s=42/2

s=21cm

a/q to heron's formula

=s s-a s-b s-c

=21 {21-18} {21-10} {21-14}

= 21{3} {11} {7}

=21{221}

=21root 221

Answer 2

Answer:

one side(a)=18cm

second side(b)=10cm

other side(c)=?

Peri of triangle=42cm

Peri of triangle=a+b+c

42cm=18cm+10cm+c

42cm=28cm+c

42cm-28cm=c

14cm=c

c=14cm

Now,

semi Peri of triangle= Peri of triangle

2

= 42 cm

2

= 21cm

heron's formula=s(s-a)(s-b)(s-c)

=21(21-18)(21-10)(21-14)

=21(3)(11)(7)

=4851cm*2