Find all angles, 0^{\circ} \leq \theta<360^{\circ} , that satisfy the equation below, to the nearest tenth of a degree.−4sin2θ−6sinθ+4=−9sinθ+3Answer: θ=
Q. Find all angles, 0∘≤θ<360∘, that satisfy the equation below, to the nearest tenth of a degree.−4sin2θ−6sinθ+4=−9sinθ+3Answer: θ=
Simplify Equation: First, we need to simplify the given equation by moving all terms to one side to set the equation to zero.−4sin2(θ)−6sin(θ)+4=−9sin(θ)+3Add 9sin(θ) to both sides and subtract 3 from both sides to get:−4sin2(θ)+3sin(θ)+1=0
Factor Quadratic Equation: Next, we factor the quadratic equation in terms of sin(θ). We look for two numbers that multiply to −4 and add up to 3. These numbers are 4 and −1. So we can write the equation as: (−4sin(θ)−1)(sin(θ)−1)=0
Solve for sin(θ): Now, we solve for sin(θ) by setting each factor equal to zero.First factor: −4sin(θ)−1=0Add 1 to both sides and then divide by −4:sin(θ)=−41
Find Angles: Second factor: sin(θ)−1=0Add 1 to both sides:sin(θ)=1
Reference Angle: We now find the angles that correspond to sin(θ)=−41 and sin(θ)=1 within the range 0 degrees to 360 degrees.For sin(θ)=1, the angle is 90 degrees.
Calculate Angles: For sin(θ)=−41, we need to find the reference angle whose sine is 41 and then find the corresponding angles in the third and fourth quadrants where sine is negative.The reference angle, which we'll call α, can be found using the inverse sine function:α=arcsin(41)≈14.5 degrees (to the nearest tenth)
Final Angles: The angles in the third and fourth quadrants corresponding to the reference angle α are:180+α and 360−α.So we have:θ1=180+14.5≈194.5 degreesθ2=360−14.5≈345.5 degrees
Final Angles: The angles in the third and fourth quadrants corresponding to the reference angle α are: 180+α and 360−α. So we have: θ1=180+14.5≈194.5 degrees θ2=360−14.5≈345.5 degrees We now have all the angles that satisfy the original equation: θ=90 degrees, 194.5 degrees, and 345.5 degrees.
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