olymmath

ÖMO 2004

Austrian Mathematical Olympiad 2004.

Other problems

Problem 5

Solve the following system of equations in real numbers: {a2=bcbcd3(b+c)(b+c+d)b2=cdcda3(c+d)(c+d+a)c2=dadab3(d+a)(d+a+b)d2=ababc3(a+b)(a+b+c)\begin{cases} a^2 = \cfrac{\sqrt{bc}\sqrt[3]{bcd}}{(b+c)(b+c+d)} b^2 =\cfrac{\sqrt{cd}\sqrt[3]{cda}}{(c+d)(c+d+a)} c^2 =\cfrac{\sqrt{da}\sqrt[3]{dab}}{(d+a)(d+a+b)} d^2 =\cfrac{\sqrt{ab}\sqrt[3]{abc}}{(a+b)(a+b+c)} \end{cases}

Problem 6

Over the sides of an equilateral triangle with area 11 are triangles with the opposite angle 60∘60^{\circ} to each side drawn outside of the triangle. The new corners are PP , QQ and RR . (and the new triangles APBAPB , BQCBQC and ARCARC ) 1)What is the highest possible area of the triangle PQRPQR ? 2)What is the highest possible area of the triangle whose vertexes are the midpoints of the inscribed circles of the triangles APBAPB , BQCBQC and ARCARC ?