1.

Find the values of the following trigonometric ratios:cosec (-\(\cfrac{20\pi}3\))

Answer»

Given cosec (-\(\cfrac{20\pi}3\))

⇒ cosec (-\(\cfrac{20\pi}3\)) = cosec(-1200°)

⇒ cosec (-1200°) = cosec (1200°)

= cosec (90° × 13 + 30)

1200° lies in second quadrant in which cosec function is positive.

∴ cosec (-1200°) = -cosec (90° × 13 + 30°)

= -sec 30°

\(-\cfrac{2}{\sqrt3}\)



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