Geometry Problem
Click the figure below to see the complete problem 456 about Three tangent circles, Center, Chord, Secant, Collinear.
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Complete Problem 456
Level: High School, SAT Prep, College geometry
Monday, May 17, 2010
Problem 456: Three tangent circles, Center, Chord, Secant, Collinear
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B, E, C are collinear (from E, EB, EC perpen to comm tg)
ReplyDeleteBDE = BED , ADG = AGD ( DB = BE = r, AD = AG = R )
=>
BED = AGD => BEC//AG (1)
CFE = CEF , AFH = AHF ( CE = CF = r, AH = AF = R )
=>
CEF = AHF => BEC//AH (2)
from (1) & (2)
from A we can draw just one parallel to a line (BEC)
H, A, G are collinear
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Problem 456
ReplyDeleteDesign all common external tangents intersect at P.(P is the radical center of three circles).
Is <DAH=2.<DFH=2.<DFE=<DPE, (PD=PE=PF), <FAG=2.<FDG=2.<FDE=<FPE and <DAF=
180-<DPF (ADPF=cyclic).Then <DAH+<FAG+<DAF=<EPD+<EPF+180-<DPE=180.
Therefore H,A and G are collinear.
APOSTOLIS MANOLOUDIS 4 HIGH SHCOOL OF KORYDALLOS PIRAEUS GREECE