Question

Find the perimeter of each of the following shapes : 

1. A triangle of sides 3 cm, 4 cm and 5 cm. 
2.  An equilateral triangle of side 9 cm. 
3.  An isosceles triangle with equal sides 8 cm each and third side 6 cm.

Answer 1

(a) \(\text{Perimeter of}\; \triangle\; ABC\) = \(AB + BC + CA\) 

= \(3\) \(cm\) + \(5\) \(cm\) + \(4\) \(cm\) 
= \(12\) \(cm\) 

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(b) \(\text{Perimeter of equilateral}\; \triangle \;ABC\) = \(3 \times side\) 

= \(3 \times 9\) \(cm\) 
= \(27\) \(cm\)

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(c) \(\text{Perimeter of}\; \triangle\; ABC\) = \(AB + BC + CA \)

= \(8\) \(cm\) + \(6\) \(cm\) + 8 \(cm\) 
= \(22\) \(cm\) 

Answer 2

Let's find the perimeter of each shape:

1. Triangle of sides 3 cm, 4 cm, and 5 cm:
The perimeter P of a triangle is the sum of the lengths of its three sides.
\(P = 3 \text{ cm} + 4 \text{ cm} + 5 \text{ cm} = 12 \text{ cm}\)

2. An equilateral triangle of side 9 cm:
In an equilateral triangle, all sides are equal. So, the perimeter is:
\(P = 9 \text{ cm} + 9 \text{ cm} + 9 \text{ cm} = 27 \text{ cm}\)

3. Isosceles triangle with equal sides 8 cm each and the third side 6 cm:
In an isosceles triangle, two sides are equal, and the third side is different. So, the perimeter is:
\(P = 8 \text{ cm} + 8 \text{ cm} + 6 \text{ cm} = 22 \text{ cm}\)

So, the answer is 12cm, 27cm and 22cm.