The area of an isosceles triangle having base 2 cm and the length of one of the equal sides 4 cm, is
a. √15 cm²
b. √15/2 cm²
c. 2√15 cm²
d. 4√15 cm²

Solution:

Given, base of an isosceles triangle = 2 cm

Length of one of the equal sides = 4 cm

We have to find the area of an isosceles triangle

Area of an isosceles triangle = a/4 √4b² - a²

Here, a = 2 cm and b = 4 cm

Area of triangle = 2/4 √4(4)² - (2)²

= 2/4 √4(16) - 4

= 2/4 √64 - 4

= 2/4 √60

= 2/4 √15 × 4

= 2√15/2

= √15 cm²

Therefore, the area of isosceles triangle is √15 cm²

✦ Try This: The area of an isosceles triangle having base 2 cm and the length of one of the equal sides 3 cm, is

Given, base of an isosceles triangle = 2 cm

Length of one of the equal sides = 3 cm

We have to find the area of an isosceles triangle

Area of an isosceles triangle = a/4 √4b² - a²

Here, a = 2 cm and b = 3 cm

Area of triangle = 2/4 √4(3)² - (2)²

= 2/4 √4(9) - 4

= 2/4 √36 - 4

= 2/4 √32

= 2/4 √16 × 2

= 4√2/2

= 2√2 cm²

Therefore, the area of isosceles triangle is 2√2 cm²

☛ Also Check: NCERT Solutions for Class 9 Maths Chapter 12

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NCERT Exemplar Class 9 Maths Exercise 12.1 Problem 8

The area of an isosceles triangle having base 2 cm and the length of one of the equal sides 4 cm, is a. √15 cm², b. √15/2 cm², c. 2√15 cm², d. 4√15 cm²

Summary:

The area of an isosceles triangle having base 2 cm and the length of one of the equal sides 4 cm, is √15 cm²

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