Understand the problem Prove that a triangle is right-angled if and only if Source of the problem Vietnam National Mathematical Olympiad 1981 Topic Trigonometry Difficulty Level Medium Suggested Book Challenge and Thrill of Pre-college Mathematics Start with hints...

Understand the problem For x ≥ 0 definef(x) =.Determine the set {y ∈ R : y = f(x), x ≥ 0}. Source of the problem I.S.I. (Indian Statistical Institute) B.Stat/B.Math Entrance Examination 2013. Subjective Problem no. 2. Topic Calculus , Function Difficulty Level...

Understand the problem Let be a real-valued function on the plane such that for every square in the plane, Does it follow that for all points in the plane? Source of the problem Putnam 2009 A1 Topic Geometry Difficulty Level Easy Suggested Book Mathematical...

Understand the problem In a badminton singles tournament, each player played against all the othersexactly once and each game had a winner. After all the games, each playerlisted the names of all the players she defeated as well as the names of all theplayers defeated...

Understand the problem Given a triangle ABC with three lattice vertices . it is known that no more lattice point lies on the edges . only one lattice point D is inside the triangle . prove that D is centroid of that triangle . Source of the problem Iran Maths...

Understand the problem Let (a,b,c) be the sides of a triangle and (A,B,C) be the angles opposite to those sides respectively. If ( sin (A-B)=frac{a}{a+b}sin Acos B-frac{b}{a+b} cos A sin B), then prove that the triangle is isosceles. Source of the problem I.S.I....