All Triangles are equilateral ( each side = 4)
Area of a Triangle is (B x H)/2. B being the base ( 4) & H the altitude.
WE know that altitude in an equilateral triangle, H = ( side x√3)/2
So H= (4√3)/2 = 2√3
The area of one triangle = (4 x 2√3)/2 = 4√3
And for the 3 triangles the lateral area = (4√3) x 3 = 12√3
