Two circles are tangent to two perpendicular lines and have their centres connected. Prove that the green triangle is right isosceles.
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The odd balance
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The stack
Three squares and three line segments. What’s the angle α?
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The green door
Two overlapping squares and a unit circle. What’s the green overlap area?
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The weather balloon
A circle with three red tangents. The tangency points are marked red. Prove that the yellow triangle is isosceles.
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A square deal II
A regular hexagon and a square share a vertex. What’s green : red?
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The antipodes
Two squares share a vertex. Four other vertices are connected as shown. Prove that the red points are collinear.
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The lorgnette
An ellipse, two circles centred in its focal points, a chord and a tangent. What is the angle α?
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And rightly so
A regular hexagon with a diagonal and a right triangle. What fraction is orange?
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Count to five
A triangle with a cevian. What’s α?
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The manta ray
A quadrilateral with connected side midpoints. What’s blue : red : yellow?