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Find the general solution of the following equation: 4cos2θ = 3. - Mathematics and Statistics

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Question

Find the general solution of the following equation:

4cos2θ  = 3.

Sum

Solution

The general solution of cos2θ = cos2α is
θ = nπ ± α, n ∈ Z.
Now,  4cos2θ  = 3

∴ cos2θ = `(3)/(4) = (sqrt(3)/2)^2`

∴ cos2θ = `(cos  pi/(6))^2      ...[∵ cos  pi/6 = sqrt(3)/(2)]`

∴ cos2θ = `cos^2  pi/6`

∴ the required general solution is given by

θ =  nπ ± `(pi)/(6)`, n ∈ Z.

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Trigonometric Equations and Their Solutions
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Chapter 3: Trigonometric Functions - Exercise 3.1 [Page 75]

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