Geometry
posted by Lizii on .
In equilateral triangle ABC, AB=3x and BC=2x+12. Find the numerical value of the perimeter of triangle ABC.

Since it's an equilateral triangle, AB=BC. 3x=2x+12, solve for x.

In an Equilateral triangle, all 3 sides are equal.
Therefore AB = BC = CA
So, 3x = 2x + 12
Subtract 2x from both sides of the equation
3x  2x = 2x + 12  2x
x = 12
Therefore AB = 3x = 3 x 12 = 36
Perimeter = AB + BC + CA = 3AB = 3 x 36 = 108