Question

Find the third side of a angle, two side of which are 18cm 10cm and the perimeter is 44cm
​

Answer 1

Answer:

Let the side of the triangle be a, b and c.

Given perimeter = a+b+c = 44cm

now,

It is given that

a = 18cm

b= 10 cm

So,

a+b+c = 44

18+10+c = 44

28 + c = 44

c = 44-28

c = 16 cm

So,

The third side of the triangle is of 16 cm

Answer 2

Explanation:

Area of triangle

s(s−a)(9−b)(s−0)

Here, s is the semi- perimeter,

and a,b,c are the sides of the triangle

Given a=18 cm, b=10 cm

and perimeter =42 cm

semi- perimeters=

2

perimeter

=

2

42

s=21cm.

Area of triangle

∴c=42−(18+10)cm =14 cm

∴ Area of triangle=

21.(21−18)(21−10)(21−14)

=

21.3.7.11

cm

2

=

3×7×3×7×11

cm

2

=

(3×7)

2

×11

cm

2

=21

11

cm

2