Using Heron's formula
Using base and height
Using 2 sides and the included angle between them
Equilateral Triangle

Using Heron's formula to calculate area of triangle

Side a:
Side b:
Side c:

Area=√ s(s-a)(s-b)(s-c)

where s is semi perimeter,s=(a+b+c)/2

Area using base and height

Base :
Height:

Area= 1/2*base*height

Area using 2 sides and included angle between them

Side a:
Side b:
Angle between them (in degrees) c

Area= 1/2*a*b*sin c


Area of equilateral triangle

Side:

Area =(√ 3)a 2/4