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UKMT Intermediate Mathematical Challenge, 2023

Geometry Difficulty 3.0 AMC 10/12 Find the answer United Kingdom

A rectangle PQRSPQRS has side-lengths aa and bb, with a<ba < b. The rectangle PTUVPTUV has side-lengths cc and dd, with c<dc < d. Also, a<da < d and c<bc < b, as shown. The sides RSRS and TUTU cross at XX. Which of these conditions guarantees that QQ, XX and VV lie on a straight line?

(A) ab+cd=1\dfrac{a}{b}+\dfrac{c}{d}=1 (B) ac+bd=1\dfrac{a}{c}+\dfrac{b}{d}=1 (C) ad+cb=1\dfrac{a}{d}+\dfrac{c}{b}=1 (D) ac+db=1\dfrac{a}{c}+\dfrac{d}{b}=1 (E) ca+bd=1\dfrac{c}{a}+\dfrac{b}{d}=1

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