Question

01. The perimeter of an isosceles triangle is 40 cm and measure of the two equal sides is 10 cm each Find
the measure of the third side of the triangle
​

Answer 1

30cm

Step-by-step explanation:

Given:

• Perimeter of an isosceles triangle =40cm
• Measure of two sides = 10cm

To find:

• Measure of the third side of the triangle.

We know that, in an isosceles triangle:

• Two sides are equal

This means:

• First side = Second Side

Let the:

• First side be a
• Second Side be b

As Measure of two sides is 10cm,

⠀⠀⇒ ⠀⠀a+b = 10

⠀⠀⇒ ⠀⠀a+a = 10

⠀⠀⇒ ⠀⠀2a = 10

⠀⠀⇒ ⠀⠀a = 5

• First Side = a = 5cm
• Second Side = b = 5cm

Let the third side be 'c'. We know that:

• Perimeter = Sum of all three sides.
• a+b+c = Perimeter

On applying the formula, we get:

⠀⠀⇒ ⠀⠀a+b+c = 40

⠀⠀⇒ ⠀⠀5+5+c = 40

⠀⠀⇒ ⠀⠀10+c = 40

⠀⠀⇒ ⠀⠀c = 40-10

⠀⠀⇒ ⠀⠀c = 30

Hence, the measure of third side is 30cm