« Vrati se
Let ABC be a triangle, and let P, Q, R be three points in the interiors of the sides BC, CA, AB of this triangle. Prove that the area of at least one of the three triangles AQR, BRP, CPQ is less than or equal to one quarter of the area of triangle ABC.

Alternative formulation: Let ABC be a triangle, and let P, Q, R be three points on the segments BC, CA, AB, respectively. Prove that

\min\left\{\left|AQR\right|,\left|BRP\right|,\left|CPQ\right|\right\}\leq\frac14\cdot\left|ABC\right|,

where the abbreviation \left|P_1P_2P_3\right| denotes the (non-directed) area of an arbitrary triangle P_1P_2P_3.

Slični zadaci

Construct a right triangle with given hypotenuse c such that the median drawn to the hypotenuse is the geometric mean of the two legs of the triangle.
Consider a plane \epsilon and three non-collinear points A,B,C on the same side of \epsilon; suppose the plane determined by these three points is not parallel to \epsilon. In plane \epsilon take three arbitrary points A',B',C'. Let L,M,N be the midpoints of segments AA', BB', CC'; Let G be the centroid of the triangle LMN. (We will not consider positions of the points A', B', C' such that the points L,M,N do not form a triangle.) What is the locus of point G as A', B', C' range independently over the plane \epsilon?
Let a,b,c be the lengths of the sides of a triangle, and \alpha, \beta, \gamma respectively, the angles opposite these sides. Prove that if a+b=\tan{\frac{\gamma}{2}}(a\tan{\alpha}+b\tan{\beta}) the triangle is isosceles.
Given 100 coplanar points, no three collinear, prove that at most 70\% of the triangles formed by the points have all angles acute.
Let a, b and c be the lengths of the sides of a triangle. Prove that
a^{2}b(a - b) + b^{2}c(b - c) + c^{2}a(c - a)\ge 0.
Determine when equality occurs.
In a right-angled triangle ABC let AD be the altitude drawn to the hypotenuse and let the straight line joining the incentres of the triangles ABD, ACD intersect the sides AB, AC at the points K,L respectively. If E and E_1 dnote the areas of triangles ABC and AKL respectively, show that
\frac {E}{E_1} \geq 2.