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Question
Without using trigonometric tables, evaluate :
`("cosec" 42^circ)/sec 48^circ`
Solution
`("cosec" 42^circ)/sec 48^circ`
= `("cosec" (90^circ - 48^circ))/sec 48^circ`
= `sec 48^circ/sec 48^circ` [`because` sec (90-θ) = cosec θ]
= 1
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