According to the question , sides are 3x , 4x and 5x.

Given perimeter = 15 cm

⇒ 3x + 4x + 5x = 15

⇒ 12x = 15

⇒ x = 1.25

Hence, sides are 3.75 cm , 5 cm and 6.25 cm.

Steps of Construction

1. Take AB= 5 cm and draw a line segment.

2. Measure 3.75 cm from ruler and draw and arc above AB. Again do the same for 6.25 cm.

3. On the point where they both intersect name it as C.

4. Join AC and CB.