Solution: Given, the equation is 18 cos(x) - 9 = 0 We have to all values of x in the interval [0, 2π] Now, 18 cos(x) = 9 cos(x) = 9/18 cos(x) = 1/2 We can use the unit circle to find which angles satisfy the equation. Points on the unit circle are (cos, sin) So, any point on the unit circle that has an x value of 1/2 is a solution. We know, cos(π/3) = 1/2 cos(5π/3) = 1/2 Therefore, the values of x are π/3, 5π/3. Find all values of x in the interval [0, 2π] that satisfy the equation. (Enter your answers as a comma-separated list.)? 18 cos(x) - 9 = 0Summary: All the values of x in the interval [0, 2π] that satisfy the equation 18 cos(x) - 9 = 0 are π/3, 5π/3. The trigonometric equation 10 cos(x) - 5 = 0 10 cos(x) = 5 cos (x) = 5/10 cos (x) = 1/2 cos (x) = cos (π/3) Principal value is x = π/3 The genaral solution of cos(θ) = cos(α) is θ = 2nπ ± α, where n is an integer. x = 2nπ ± (π/3) If n = 0, x = 2(0)π + (π/3) and x = 2(0)π - (π/3) = π/3 and - π/3. If n = 1, x = 2(1)π + (π/3) and x = 2(1)π - (π/3) = 2π + π/3 and 2π - π/3 = 7π/3 and 5π/3. Therefore, the solutions of the given equation are x = π/3, x = 5π/3 and x = 7π/3 in the interval [0, 2π]. Explanation:First isolate X: What are the solutions in the interval 0 ≤ θ 2π?The solutions within the domain 0 ≤ θ < 2 π 0 ≤ θ < 2 π are 0 , π , 7 π 6 , 11 π 6 .
Does 0 2pi include 0?All numbers between 0 and 2π , including the 0 and 2π , are included.
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