Evaluate:
sec 75°cosec 15°\dfrac{\text{sec 75°}}{\text{cosec 15°}}cosec 15°sec 75°
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sec 75°cosec 15°=sec (90° - 15°)cosec 15°=cosec 15°cosec 15°=cosec15°cosec15°=1\dfrac{\text{sec 75°}}{\text{cosec 15°}} = \dfrac{\text{sec (90° - 15°)}}{\text{cosec 15°}}\\[1em] = \dfrac{\text{cosec 15°}}{\text{cosec 15°}}\\[1em] = \dfrac{\cancel{cosec 15°}}{\cancel{cosec 15°}}\\[1em] = 1cosec 15°sec 75°=cosec 15°sec (90° - 15°)=cosec 15°cosec 15°=cosec15°cosec15°=1
Hence, sec 75°cosec 15°\dfrac{\text{sec 75°}}{\text{cosec 15°}}cosec 15°sec 75° = 1.
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