<Solid-2025-255>, hint
Let E be a point on CD and HE is perpendicular to CD.
Since HH' is orthogonal to plane ACD, A, B, H, H' E are collinear
Suppose AE>BE and rotate ACD so that ACD and BCD lie on the same plane
Let M be the midpoint of CD. Since MG:GB=1:2=MG':G'A, G,G', F are collinear
F is the orthogonal projection of G, G' onto CD
GF=1/3 BE(h), G'F=1/3AE(h') GF/G'F=h/h'
HE=CE cot CHE=CE cot CDB=CE (ED/BE)=(CE ED)/h
H'E=CE cot CH'E=CE cot CDA=CE(ED/AE)=(CE ED)h'
GF/G'F=h/h'=H'E/HE
No comments:
Post a Comment