Thứ Sáu, 12 tháng 9, 2014

30-Fermat point, Incenter, and Equilateral triangles

Let ABC be a triangle, let I is the incenter and F_+,F_- the first and the secon Fermat points. Construct circle with center I and radii \frac{2r}{3}r is radii of incircle. This circle meet three sie AB.BC,CA at A_c,B_c,B_a,C_a,C_b,A_b. Prove that:


Define: A_+,B_+,C_+ are center of three circles (F_+A_cB_c), (F_+B_aC_a), (F_+C_bA_b). Define: A_-,B_-,C_- are center of three circles (F_-A_cB_c), (F_-B_aC_a), (F_-C_bA_b)



1-A_+B_+C_+ is an equilateral triangle.
2- A_-B_-C_- is an equilateral triangle.
3- A_+B_+C_+ homothetic the first Isodynamic Equileteral triangle (respectively with X_{15})
4-A_-B_-C_- homothetic the secon Isodynamic Equileteral triangle (respectively with X_{16})
5- A_+B_+C_+ perspective with the first Napoleon Equileteral triangle (respectively with X_{17})
6-A_-B_-C_- perspective with the secon Napoleon Equilateral triangle (respectively with X_{18})

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