who calculated the volume of pyramids and cones
Cavalieri's principle The fact that the volume of any pyramid, regardless of the shape of the base, whether circular as in the case of a cone, or square as in the case of the Egyptian pyramids, or any other shape, is (1/3) × base × height, can be established by Cavalieri's principle if one knows only that it is true in one case. One may initially establish it in a single case by partitioning the interior of a triangular prism into three pyramidal components of equal volumes. One may show the equality of those three volumes by means of Cavalieri's principle.
Great Pyramid of Giza It is believed by Egyptologists that the pyramid was built as a tomb for Fourth Dynasty Egyptian pharaoh Khufu (often Hellenicised as "Cheops") and was constructed over a 20-year period. Khufu's vizier, Hemiunu (also called Hemon), is believed by some to be the architect of the Great Pyramid.[2] It is thought that, at construction, the Great Pyramid was originally 280 Egyptian cubits tall (146.5 metres (480.6 ft)), but with erosion and absence of its pyramidion, its present height is 138.8 metres (455.4 ft). Each base side was 440 cubits, 230.4 metres (755.9 ft) long. The mass of the pyramid is estimated at 5.9 million tonnes. The volume, including an internal hillock, is roughly 2,500,000 cubic metres (88,000,000 cu ft).[3]