Find the area of a triangle two sides of which are 18cm and 10cm and the perimeter is 42cm
Solution:
Given: Two sides of the triangle and its perimeter.
By using Heron’s formula, we can calculate the area of triangle.
Heron's formula for the area of a triangle is: Area = √s(s - a)(s - b)(s - c)
Where a, b and c are the sides of the triangle, and s = Semi-perimeter = Half the perimeter of the triangle
The sides of triangle given: a =18 cm, b = 10 cm
Perimeter of the triangle = (a + b + c)
42 = 18 + 10 + c
42 = 28 + c
c = 42 - 28
c = 14 cm
Semi Perimeter
s = (a + b + c) = 42/2 = 21 cm
By using Heron’s formula,
Area of a triangle = √s(s - a)(s - b)(s - c)
= √21(21 - 18)(21 - 10)(21 - 14)
= √21 × 3 × 11 × 7
= 21√11 cm2
Area of the triangle = 21√11 cm2.
☛ Check: Class 9 Maths NCERT Solutions Chapter 12
Video Solution:
Find the area of a triangle two sides of which are 18cm and 10cm and the perimeter is 42cm
Class 9 Maths NCERT Solutions Chapter 12 Exercise 12.1 Question 4
Summary:
It is given that in a given triangle two sides are 18cm and 10cm and the perimeter is 42cm. We have found its area equal to 21√11 cm2.
☛ Related Questions:
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