Q. Find all angles, 0∘≤θ<360∘, that satisfy the equation below, to the nearest tenth of a degree.4cos2θ=4cosθ−1Answer: θ=
Rewrite Equation: Rewrite the given equation in standard quadratic form.The given equation is 4cos2(θ)=4cos(θ)−1. To solve for θ, we need to rewrite this equation in the form of a quadratic equationax2+bx+c=0.Subtract 4cos(θ) and add 1 to both sides to get:4cos2(θ)−4cos(θ)+1=0
Factor Quadratic: Factor the quadratic equation.The equation 4cos2(θ)−4cos(θ)+1=0 is a quadratic equation in terms of cos(θ). We can factor this equation as:(2cos(θ)−1)2=0
Solve for cos(θ): Solve for cos(θ). Since we have a perfect square, we can take the square root of both sides to get: 2cos(θ)−1=0 Now, add 1 to both sides: 2cos(θ)=1 Divide both sides by 2: cos(θ)=21
Find Corresponding Angles: Find the angles that correspond to cos(θ)=21. The cosine function is positive and equals 21 at specific angles within the range of 0∘ to 360∘. These angles are 60∘ and 300∘, as cosine is positive in the first and fourth quadrants.
Check Additional Solutions: Check for any additional solutions within the given range.Since the cosine function is periodic with a period of 360°, we need to check if there are any other angles within the range of 0° to 360° that satisfy the equation. However, since we have already identified the angles where cos(θ)=21 within one period, there are no additional solutions.
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