Q5 of 33 Page 12

Find the area of a triangle two sides of which are 4 cm and 8 cm and the perimeter is 20 cm.

Given: Perimeter of triangle = 20 cm

Two sides of triangle = 4 cm and 8 cm


To Find: Area of the triangle


Concept Used:


If sides of a triangle are a, b, and c, then area of a triangle is given by:



Where s = semiperimeter of the triangle



The perimeter of triangle = Sum of sides of the triangle


Assumption: Let the sides of the triangle be, a, b, and c such that


a = 4 cm, b = 8 cm and a + b + c = 20 cm


Explanation:


a + b + c = 20 cm


4 + 8 + c = 20


12 + c = 20


c = 8 cm





s = 10 cm





Area = 4√15 cm2.


Hence, the area of the triangle is 4√15 cm2.


More from this chapter

All 33 →
3

Prove that the area of an equilateral triangle is .

4

If each side of a triangle is doubled, then find percentage increase in its area.

 6

The perimeter of a triangular field is 420 cm, and its sides are in the ratio 2:2:3. Find the area of the triangular field.

 7

If the ratio of area and perimeter of an equilateral triangle is 4√3, find the area of a triangle.