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Many of the problems in this feature include proof sorting activities which challenge you to rearrange statements in order to recreate clear, rigorous proofs.

Plus magazine has a selection of interesting articles exploring proofs in which pictures play an important role.

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### Circumference angles

Can you prove the angle properties described by some of the circle theorems?

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### Cyclic Quadrilaterals Proof

Can you prove that the opposite angles of cyclic quadrilaterals add to $180^\circ$?

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### Pythagoras Proofs

Can you make sense of these three proofs of Pythagoras' Theorem?

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### Pentakite

Given a regular pentagon, can you find the distance between two non-adjacent vertices?

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### Quad in Quad

Join the midpoints of a quadrilateral to get a new quadrilateral. What is special about it?

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### Kite in a Square

Can you make sense of the three methods to work out what fraction of the total area is shaded?

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### The Converse of Pythagoras

Can you prove that triangles are right-angled when $a^2+b^2=c^2$?

*We are very grateful to the Heilbronn Institute for Mathematical Research for their generous support for the development of these resources.*