Share

# Find the area of a triangle two sides of which are 18 cm and 10 cm and the perimeter is 42 cm. - CBSE Class 9 - Mathematics

ConceptArea of a Triangle by Heron’S Formula

#### Question

Find the area of a triangle two sides of which are 18 cm and 10 cm and the perimeter is 42 cm.

#### Solution

Let the third side of the triangle be x.

Perimeter of the given triangle = 42 cm

18 cm + 10 cm + = 42

x = 14 cm

s = "Perimeter"/2=42/2=21cm

By Heron's formula,

"Area of a triangle "=sqrt(s(s-a)(s-b)(s-c))

"Area of the given triangle "=(sqrt(21(21-18)(21-10)(21-14)))cm^2

=(sqrt(21(3)(11)(7)))cm^2

= 21sqrt11 cm^2

Is there an error in this question or solution?

#### APPEARS IN

NCERT Solution for Mathematics Class 9 (2018 to Current)
Chapter 12: Heron's Formula
Ex. 12.10 | Q: 4 | Page no. 203

#### Video TutorialsVIEW ALL [1]

Solution Find the area of a triangle two sides of which are 18 cm and 10 cm and the perimeter is 42 cm. Concept: Area of a Triangle by Heron’S Formula.
S