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Find the principal solution of the following equation: cosθ = 12 - Mathematics and Statistics

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प्रश्न

Find the principal solution of the following equation: 

cosθ = `(1)/(2)`

बेरीज

उत्तर

We know that, `cos  pi/(3) = 1/2` and cos(2π - θ) = cosθ

`∴ cos  π/3 = cos(2pi - pi/3) = cos  (5pi)/3`

`∴ cos  pi/3 = cos  (5pi)/3 = 1/2`, where

`0 < pi/3 < 2pi and  0 < (5pi)/3 < 2pi`

`∴ cosθ = 1/2 "gives" cosθ = cos  pi/(3) = cos  (5pi)/(3)`

∴ θ = `pi/(3) and θ = (5pi)/(3)`

Hence, the required principal solutions are

`θ = pi/(3) and θ = (5pi)/(3)`.

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Trigonometric Equations and Their Solutions
  या प्रश्नात किंवा उत्तरात काही त्रुटी आहे का?
पाठ 3: Trigonometric Functions - Exercise 3.1 [पृष्ठ ७५]

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