A triangle is 3 sided 2D shape. Any side of the triangle which is perpendicular to the height is termed as the base. It can be taken into account that any of the three sides of a triangle can be a base. The height of the triangle corresponds to its base, so whenever base length changes, height also changes. From this online Base of a triangle calculator, you can find the length of a base triangle from the known values of angle, side length and area of the triangle.
A triangle has an area of 30cm^2, angle of 60° and side of 6 cm,
Base of a triangle = 2×(30/ (6×sin(60)))
= 11.547 cm