This paper demonstrates that the Great Pyramid of Giza is originally a 60-degree pyramid, in general, it is an equilateral triangle, whereas its inclination angle is exactly 60°, not the theoretical angle 51° 52ˊ (51.86°), postulated by John Taylor in 1859. Therefore, the original vertical height of the pyramid would be 199.47 meters, not 146.6 meters, while the original inclined height of the pyramid would be equal to the length of its base side, equals 230.34 meters.
This inclined height of the pyramid, is what Herodotus and many early authors in the middle ages meant in their description for the dimensions of the Great Pyramid, as they stated a height of the pyramid equals to the base's length, without clarifying weather they meant the vertical height, or the inclined height of the pyramid, but according to the description of the Great Pyramid by Ali ibn Ridwan, a famous Egyptian astronomer in the 11th century AD/ the 6th century AD, it turns out that they meant the inclined height (Apotheme), the line from the pyramid top to the middle of the base side, not the vertical height, that to be equal to the length of the base side of the pyramid.
This was confirmed by Pliny's measurement of the Great Pyramid in the classical era, after stating the method of measuring the pyramid's vertical height, and emphasized by as Charles Perry in 1743. Therefore, the researcher has used the descriptive analytical Approach through this paper to come out to his conclusion.