MathLabs

Problem 4

Let A0B0C0A_0B_0C_0 and A1B1C1A_1B_1C_1 be any two acute-angled triangles. Consider all triangles ABCABC similar to A1B1C1A_1B_1C_1 (with corresponding vertices) and circumscribed about A0B0C0A_0B_0C_0, where A0A_0 lies on BCBC, B0B_0 on CACA, and C0C_0 on ABAB. Determine and construct the triangle of maximum area.
Step 1 of 7: Choose a reference triangle
A0∈YZ,B0∈ZX,C0∈XYA_0\in YZ,\quad B_0\in ZX,\quad C_0\in XY
Detailed analysis

Choose any admissible triangle XYZXYZ similar to A1B1C1A_1B_1C_1, labeled so that A0A_0 lies on YZYZ, B0B_0 on ZXZX, and C0C_0 on XYXY. Such a triangle is obtained by choosing a line through A0A_0 and drawing the other two sides at the prescribed angles.