Answer:
19cm
Step-by-step explanation:
An equilateral triangle is a triangle where the length of the 3 sides are the same.
the perimeter is the sum of the 3 sides
for example, if the length of the side of the an equilateral triangle is 5, the perimeter is 5 x 3 = 15
let x = unknown length of side
length after increase = x + 5
(x + 5) x 3 = 72
divide both sides of the equation by 3
x + 5 = 24
subtract 5 from both sides of the equation
x = 24 - 5 = 19cm
