Detroit. Public schools. Dept. of instruction, teacher training and research. [from old catalog], Kepler, Frank Roy. [from old catalog] · Detroit · leaf 23
found byprojecting from p. 22 To develop a right circular cone:—It is evident that in aright circular cone all the elements are of equal length. Theline 0^-1 ^ is the true length of one of these elements, Fig. 26.Why? With a radius 0-1^, draw an arc setting off distances1^-2^, 2i-3i equal to the… … Since all the elements are equal, the true length of theelement 0-3 coincides with O-l^, and the true length of thedistance 0-a will be shown at O-ai. Why? See the pyramid,Pig. 20. The true distance from the apex to any point on anyof the other elements may be found in the same way. 23…
Projection
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