If x is the side of an equilateral triangle, then the
Altitude (h) =$$\frac{\sqrt{\ 3}}{2}x$$
Area =$$\frac{\sqrt{\ 3}}{4}x^2$$
Inradius = $$\frac{1}{3}\times\ h$$
Circumradius = $$\frac{2}{3}\times\ h$$
▪ Area of an isosceles triangle =$$\frac{a}{4}\sqrt{\ 4c^2-a^2}$$ (where a, b and c are the lengths of the sides of BC, AC and AB, respectively, b = c).
