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Pls help i don’t get this

Pls help i don’t get this-example-1
User Seyi
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1 Answer

3 votes

Answer:

2π/3 + 2πn or 4π/3 + 2πn radians

Explanation:

Think of this as a quadratic function: replace the cos(x) with “x”.

2x^2 - 7x - 4 = 0

Now factor it

(2x + 1)(x - 4) = 0

Now, replace the “x” with cos(x) and solve

(2cos(x) + 1)(cos(x) - 4) = 0

2cos(x) + 1 = 0

cos(x) = -1/2

x = 2π/3 + 2πn or 4π/3 + 2πn radians


cos(x) = 4

x is undefined here

User Matteo Scotuzzi
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8.3k points

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