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Question
Without using trigonometric table , evaluate :
`sin72^circ/cos18^circ - sec32^circ/(cosec58^circ)`
Solution
`sin72^circ/cos18^circ - sec32^circ/(cosec58^circ)`
⇒ `sin(90^circ - 18^circ)/cos18^circ - sec(90^circ - 58^circ)/(cosec58^circ)`
⇒ `cos18^circ/cos18^circ - (cosec 58^circ)/(cosec58^circ) = 1 - 1 = 0`
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