What is the area of the trapezium in terms of lengths a and b?
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The road less traveled
Category: Beginner
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The night sky
A semicircle containing two equilateral triangles and a circle. What’s the yellow fraction?
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The parachute
A circular sector is divided as shown. What fraction is red?
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Move the earth
A square containing a semicircle, a tangent and a line segment from the tangency point. What fraction is green?
A regular hexagon, a square with its diagonals, an equilateral triangle and a circle. Prove that the hexagon and the circle are concentric.
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The common triangle
Two semicircles contain a triangle. The centre of the right semicircle is shown. Prove that the triangle is isosceles.
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The fried egg
Two concentric circles and two tangents. What is the yellow fraction?
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The parallax effect
Two intersecting circles with a triangle that passes through their centres and an intersection point. What’s the angle α?
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The purple hat
A circle with three tangents forming an isosceles triangle. Two tangency points are shown. What is the proportion green : red?
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The parrot
Two squares, a diagonal and a line segment. What is red : blue : green?