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Question
Evaluate: `(cos70°)/(sin20°) + (cos59°)/(sin 31°) - 8 sin^2 30°`
Sum
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Solution
`(cos70°)/(sin20°) + (cos59°)/(sin 31°) - 8 sin^2 30°`
= `(cos(90° - 20°))/(sin20°) + (cos(90° - 31°))/(sin31°) - 8(1/2)^2`
= `(sin20°)/(sin20°) + (sin31°)/(sin31°) - 2`
= 1 + 1 - 2
= 0
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