Two semicircles and several line segments. Prove that the red line segments are parallel.
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Uneven cups
Tag: triangle
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The glass splinter
A triangle of which two sides and one angle are given. What’s the angle α?
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The triskelion
A circle containing an equilateral triangle and three squares. What fraction is purple?
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The Christmas star
Two congruent concentric equilateral triangles. Prove that the gold fraction is red/blue.
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The forward lean
A square with a diagonal and an isosceles triangle. What fraction is brown?
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Pushing the boundary
Two equilateral triangles are placed side by side. What’s the proportion green : red?
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The Pyramid of Austerlitz
An equilateral triangle and a parabola that is tangent to two of its sides in two vertices. Proof that the triangle centre coincides with the parabola focus.
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The skewed tree
A triangle with a line segment through its centroid and parallel to a side. What faction is dark green?
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A clear vision
A circle containing a regular pentagon and two equilateral triangles. All shown points are on the circle. What’s the angle α?
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Orange above
A square contains a right triangle. What fraction is orange?