A triangle containing a semicircle and a circular sector centred in the right vertex. What is blue : green?
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The dirty thirties
Tag: triangle
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Scratching the surface
Three tangent semicircles and two coloured triangles. What’s the proportion yellow : green?
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To the core
A non-isosceles triangle with a red cevian and three line segments to a point on the cevian. Prove that this point is the incentre of the triangle.
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The seventh bell
A regular hexagon shares a vertex with an equilateral triangle of area 7. What is the area of the hexagon?
A square contains a yellow right triangle with an area of 11. What is the square’s area?
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The erratic spider
A square with several line segments. Prove that the blue ones are parallel.
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Almost sunk
A square contains a right triangle. What fraction is red?
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The side mirror
An isosceles triangle and an external point with three line segments. Prove that the red points form a cyclic quadrilateral.
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The Santos conundrum
A triangle is divided by three line segments into five smaller triangles. What is its area expressed in terms of areas A, B and C?
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Two brotherly pines
Three triangles are glued together. The green ones are based on a common line. What’s the angle α?