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Starting with: 2sin(θ)=2−cos(θ)2sin(θ)=2−cos(θ)
Square both sides of the equation:
4sin2(θ)=4−4cos(θ)+cos2(θ)4sin2(θ)=4−4cos(θ)+cos2(θ)
As sin2(θ)=1−cos2(θ)sin2(θ)=1−cos2(θ), we can rewrite the equation as:
4−4cos2(θ)=4−4cos(θ)+cos2(θ)4−4cos2(θ)=4−4cos(θ)+cos2(θ)
Adding 4cos2(θ)−44cos2(θ)−4 to both sides of the equation:
0=5cos2(θ)−4cos(θ)0=5cos2(θ)−4cos(θ)
Factorising: cos(θ).[5cos(θ)−4]=0cos(θ).[5cos(θ)−4]=0
cos(θ)∈{0,0.8}cos(θ)∈{0,0.8}
cos2(θ)∈{0,0.64}cos2(θ)∈{0,0.64}
sin2(θ)∈{1,0.36}sin2(θ)∈{1,0.36}
sin(θ)∈{−1,1,−0.6,0.6}
Starting with: 2sin(θ)=2−cos(θ)2sin(θ)=2−cos(θ)
Square both sides of the equation:
4sin2(θ)=4−4cos(θ)+cos2(θ)4sin2(θ)=4−4cos(θ)+cos2(θ)
As sin2(θ)=1−cos2(θ)sin2(θ)=1−cos2(θ), we can rewrite the equation as:
4−4cos2(θ)=4−4cos(θ)+cos2(θ)4−4cos2(θ)=4−4cos(θ)+cos2(θ)
Adding 4cos2(θ)−44cos2(θ)−4 to both sides of the equation:
0=5cos2(θ)−4cos(θ)0=5cos2(θ)−4cos(θ)
Factorising: cos(θ).[5cos(θ)−4]=0cos(θ).[5cos(θ)−4]=0
cos(θ)∈{0,0.8}cos(θ)∈{0,0.8}
cos2(θ)∈{0,0.64}cos2(θ)∈{0,0.64}
sin2(θ)∈{1,0.36}sin2(θ)∈{1,0.36}
sin(θ)∈{−1,1,−0.6,0.6}
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