InterviewSolution
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Find the general solutions of the following equations :cosec x = - \(\sqrt2\) |
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Answer» Ideas required to solve the problem: The general solution of any trigonometric equation is given as – • sin x = sin y, implies x = nπ + (– 1)ny, where n ∈ Z. • cos x = cos y, implies x = 2nπ ± y, where n ∈ Z. • tan x = tan y, implies x = nπ + y, where n ∈ Z. Given, cosec x= -\(\sqrt2\) We know that sin x, and cosec x have negative values in the 3rd and 4th quadrant. While giving a solution, we always try to take the least value of y The fourth quadrant will give the least magnitude of y as we are taking an angle in a clockwise sense (i.e., negative angle) - √2 = -cosec \((\frac{π}4)\) = cosec \((-\frac{π}4)\) { ∵ sin - θ = - sin θ} ∴ cosec x = cosec\((-\frac{π}4)\) ⇒ sim x = sin \((\frac{-π}4)\) If sin x = sin y ,then x = nπ + (– 1)ny , where n ∈ Z. For above equation y = \(-\frac{π}4\) ∴ x = nπ + (-1)n \((-\frac{π}4)\) ,where n ϵ Z Or x = nπ + (-1)n+1 \((\frac{π}4)\),where n ϵ Z Thus, x gives the required general solution for given trigonometric equation. |
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