The base of a cone is a circle. The area of a circle is found by multiplying the diameter by Pi.
If you mean, to calculate the volume, for ANY pyramid, and for cones as well, the formula is: V = (1/3)Bh, that is 1/3 times the base area, times the height. The height must be calculated perpendicular to the area that contains the base.
The base of a rectangle is a length and does not have any area. Therefore, the area can not be calculated.
The same as you would calculate any other area. For example, if the base happens to be rectangular, you multiply length x width.
Area = 0.5*base*altitude
democritus calculated the volume of pyramids and cones
no The area of a cone is 1/3 times the base times the height, so the volumes are the same only if the area of the base times the height is the same in both cones.
Cones and pyramids have only one base, but prisms have multiple bases.
Area in square units = base*height
Cones and cylinders are different shapes. Likewise you could not calculate the area of a square with the formula for a triangle.
area of a square is base times height area of a triangle is base times height divided by two!!
bigger base + smaller base x height/2
Pyramids, no; cones, yes (except the base).