Q. Find all angles, 0∘≤θ<360∘, that satisfy the equation below, to the nearest tenth of a degree.8cos2θ+6cosθ−2=−3
Rewrite Equation: Rewrite the equation to have zero on one side.8cos2(θ)+6cos(θ)−2+3=08cos2(θ)+6cos(θ)+1=0
Factor Quadratic: Factor the quadratic equation.(2cos(θ)+1)(4cos(θ)+1)=0
Solve for cos(θ): Solve for cos(θ) by setting each factor equal to zero.2cos(θ)+1=0 and 4cos(θ)+1=0
Find Angles: Solve the first equation for cos(θ).cos(θ)=−21
Check Range: Find the angles for cos(θ)=−21.θ=120 degrees and θ=240 degrees
Check Range: Find the angles for cos(θ)=−21.θ=120 degrees and θ=240 degrees Solve the second equation for cos(θ).4cos(θ)+1=0cos(θ)=−41
Check Range: Find the angles for cos(θ)=−21.θ=120 degrees and θ=240 degrees Solve the second equation for cos(θ).4cos(θ)+1=0cos(θ)=−41Find the angles for cos(θ)=−41 using a calculator.θ≈104.5 degrees and θ≈255.5 degrees
Check Range: Find the angles for cos(θ)=−21.θ=120 degrees and θ=240 degrees Solve the second equation for cos(θ).4cos(θ)+1=0cos(θ)=−41Find the angles for cos(θ)=−41 using a calculator.θ≈104.5 degrees and θ≈255.5 degrees Check if all found angles are within the specified range.0≤θ<360All angles are within the range.