The sides of the triangle are 5cm, 3cm and 7cm. Find the sides of a similar triangle with a perimeter of 105 cm.

For such figures, the ratio of the length of the side of one figure to the length of the corresponding side of the other figure is the same value for all sides and is called the coefficient of similarity. Moreover, this coefficient has the same meaning for the perimeters of such figures, since the perimeter is the sum of the lengths of all sides.

Find the perimeter of the first triangle:

5 + 3 + 7 = 15 cm.

Let’s find the coefficient of similarity from the ratio of perimeters:

105/15 = 7.

Let’s find the lengths of the sides of the second triangle:

5 * 7 = 35 cm.

3 * 7 = 21 cm.

7 * 7 = 49 cm.