Question

Activity 3
The sides of a triangle are in the ratio 3:5:7 and its perimeter is 45 cm. What are the
lengths of the sides?
Take the first side as 3x
Second side
Third side
Given Perimeter
= 45 cm
+
=45
cm
First side
Second side
Third side​

Answer 1

Appropriate Question :

The sides of a triangle are in the ratio 3:5:7 and its perimeter is 45 cm. What are the

lengths of the sides?

Given :

• Ratio of the sides of a triangle = 3 : 5 : 7

• Perimeter of the triangle = 45 cm

To find :

• Length of the three sides

Solution :

Let the three sides be 3x, 5x and 7x.

• First side = 3x
• Second side = 5x
• Third side = 7x

Using formula,

• Perimeter of triange = a + b + c

where,

• a, b and c are the first, second and third side of the triangle respectively.

Substituting the given values :-

→ 3x + 5x + 7x = 45

→ 15x = 45

→ x = 45 ÷ 15

→ x = 3

→ The value of x = 3

Substitute the value of x in the sides of triangle which we've assumed :-

→ First side = 3x = 3 × 3 = 9 cm

→ Second side = 5x = 5 × 3 = 15 cm

→ Third side = 7x = 7 × 3 = 21 cm

Therefore, the three sides of triangle are 9 cm, 15 cm and 21 cm

Answer 2

Answer:

let the sides of triangle be 3x,5x and 7x

Step-by-step explanation:

3x+5x+7x=45cm

15x=45

x=45/15

x=3

__________

first side:-

3x=3X3=9cm

second side:-

5x=5X3=15cm

third side:-

7x=7X3=21cm

therefore, the sides of triangle are 9cm,15cm,21cm