Consider a right-angle triangle ΔABC, right-angled at point B

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If AC is 13k, AB will be 12k, where k is a positive integer.

Applying Pythagoras theorem in ΔABC, we obtain

(AC)² = (AB)² + (BC)²

(13k)² = (12k)² + (BC)²

169k² = 144k² + BC²

25k² = BC²

BC = 5k

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Cos θ =

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Tan θ =

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Cot θ =

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