Two congruent circles and a right triangle inside a semicircle. What fraction is blue?
Three squares and three shared vertices. Prove that the orange quadrilateral is in fact a parallelogram.
A regular pentagon with a diagonal. What is the top angle of the isosceles triangle?
A regular pentagon with a diagonal and an extended side. What is the top angle of the isosceles triangle?
Three squares and three shared vertices. Prove the three red vertices are collinear.
A rectangle inside a square. One of its sides is tangent to the quarter circle. What fraction is green as x approaches 0?
A circle with four chords. Two chord lengths are given. What is the circle area?
Two congruent isosceles triangles and three lines. Prove triangle AEF is also isosceles.
In a small square two perpendicular lines are drawn. A larger parallel square is constructed as shown. Prove it is a scaled copy of the smaller square but rotated 90° anticlockwise.
A triangle with an inscribed rectangle. What is the maximum red fraction?