Solve the following quadratic trig equations algebraically (without graphing technology) for the domain 0 ≤ x ≤ 360°. Use exact solutions whenever possible. a.6cos2(θ) + cos(θ) - 1 = 0
b.2 - 2sin2(θ) = cos(θ)

Question

Solve the following quadratic trig equations algebraically (without graphing technology) for the domain 0 ≤ x ≤ 360°. Use exact solutions whenever possible. a.6cos2(θ) + cos(θ) - 1 = 0 
b.2 - 2sin2(θ) = cos(θ)

anonymous · Answer

$$6\cos^2\theta + \cos\theta-1=0\
(3\cos\theta-1)(2\cos\theta+1)=0\
\cos\theta=-\tfrac{1}{2},\tfrac{1}{3}$$
Can you try it from here?