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MathNet 2020 — Math Olympiad Vault — Part 06 Question 84

Math Olympiad Vault · MathNet 2020 — Math Olympiad Vault — Part 06

Question 84

In the triangle $ABC$ $\angle A=75^\circ$ and $\angle C=45^\circ$. Points $P$ and $T$ are chosen on the segments $AB$ and $BC$ in such a way that quadrilateral $APTC$ is cyclic and $CT = 2AP$. Point $O$ is the circumcenter of $\triangle ABC$. The ray $TO$ crosses side $AC$ in a point $K$. Prove that $TO=OK$.

(Anton Trygub)

Editorial note: the source refers to Figure 30, but no corresponding image is supplied; the construction and proof are specified in the text.