Q. Find all angles, 0∘≤θ<360∘, that satisfy the equation below, to the nearest tenth of a degree.4sin2θ+sinθ=0Answer: θ=
Factor equation: Factor the given trigonometric equation.The equation given is 4sin2(θ)+sin(θ)=0. We can factor out sin(θ) from both terms.sin(θ)(4sin(θ)+1)=0
Set equal and solve: Set each factor equal to zero and solve for θ. We have two factors: sin(θ) and (4sin(θ)+1). Setting each equal to zero gives us two separate equations to solve: 1. sin(θ)=02. 4sin(θ)+1=0
Solve sin(θ)=0: Solve the first equation sin(θ)=0. The sine function is equal to zero at 0∘ and 180∘ within the range of 0∘ to 360∘. Therefore, θ=0∘ and θ=180∘.
Solve 4sin(θ)+1=0: Solve the second equation 4sin(θ)+1=0 for θ.Subtract 1 from both sides to isolate the sine term:4sin(θ)=−1Divide both sides by 4:sin(θ)=−41
Find angles for sin(θ)=−41: Find the angles that correspond to sin(θ)=−41. Since the sine function is negative, we are looking for angles in the third and fourth quadrants where sine is negative. Using the inverse sine function on a calculator, we find the reference angle: θ=arcsin(41)≈14.5∘
Determine angles in quadrants: Determine the actual angles in the third and fourth quadrants.For the third quadrant, we add 180∘ to the reference angle:θ≈180∘+14.5∘=194.5∘For the fourth quadrant, we subtract the reference angle from 360∘:θ≈360∘−14.5∘=345.5∘
Combine all solutions: Combine all the solutions.The angles that satisfy the equation 4sin2(θ)+sin(θ)=0 are:θ=0∘, θ=180∘, θ=194.5∘, and θ=345.5∘.
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