When any of the side is not given, the perimeter can be found as x+y+z. As when I asked u for detail, u said it is an equilateral triangle. Therefore, IN AN EQUILATERAL TRIANGLE, ALL SIDES ARE EQUAL. Therefore, the perimeter is 3x.
as x+x+x = 3x.
In an equilateral triangle, all the angles are 60 degree.
The area of the equilateral triangle is always,
√3/4 a² unit sq.
Hope this will help you.