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In the figure below, points A, B and C are collinear. If $AC = 40$ inches, then which of the following equations does not hold true?

$ x = \cfrac{20}{\cos 50°} $

$ y = 20 \tan 50° $

$ x = \cfrac{20}{\cot 50} $

$ y = x \sin 50° $

$ x = 20 \sec 50° $