List questions from euclidean-geometry

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Mixtilinears and Symmedians

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Proofs through transformations

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124

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In a cyclic pentagon $ABCDE$, prove $\frac{a}{\sin(B+E)}=\frac{d}{\sin(C+E)}$

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Prove that $N,R,F$ are collinear

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Given two circles externaly tangent to each other and the common tangent line. Draw a third tangent circle.

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Sum of the diameters of the incircle and excircle is congruent to the sum of the segments of the altitudes from the orthocenter to the vertices.

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Intersection of Convex Sets: Simple Topology/Geometry

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441

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The bisector of the exterior angle at vertex C of triangle ABC intersects the circumscribed circle at point D. Prove that AD=BD

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67

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Circles and enneagon

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Distance from center of circle to point on line segment

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Prove that $r^2+ r_1^2+ r_2^2 +r_3^2=16R^2-a^2-b^2-c^2$

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Proving an exercise from my High School Geometry Class

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pack equilateral triangle

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Is there a theorem of intersecting chords in an ellipse?

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List Question

Orthogonal circles and chords

Mixtilinears and Symmedians

Proofs through transformations

In a cyclic pentagon $ABCDE$, prove $\frac{a}{\sin(B+E)}=\frac{d}{\sin(C+E)}$

Prove that $N,R,F$ are collinear

Given two circles externaly tangent to each other and the common tangent line. Draw a third tangent circle.

Sum of the diameters of the incircle and excircle is congruent to the sum of the segments of the altitudes from the orthocenter to the vertices.

Intersection of Convex Sets: Simple Topology/Geometry

The bisector of the exterior angle at vertex C of triangle ABC intersects the circumscribed circle at point D. Prove that AD=BD

Circles and enneagon

Distance from center of circle to point on line segment

Prove that $r^2+ r_1^2+ r_2^2 +r_3^2=16R^2-a^2-b^2-c^2$

Proving an exercise from my High School Geometry Class

pack equilateral triangle

Is there a theorem of intersecting chords in an ellipse?

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