Question

What is 6cos square theta+cos theta -2=0 what the theta in degrees

Answer 1

Answer:
`\begin{gathered} \theta=60^o \\ OR \\ \theta=131.8^o \end{gathered}`

Step-by-step explanation:

Given:

`6\cos^2\theta+\cos\theta-2=0`

Let

`\cos\theta=t`

Then

`\begin{gathered} 6t^2+t-2=0 \\ (2t-1)(3t+2)=0 \\ 2t-1=0 \\ \Rightarrow t=(1)/(2) \\ \\ 3t+2=0 \\ \Rightarrow t=-(2)/(3) \end{gathered}`

Therefore:

`\begin{gathered} \cos\theta=(1)/(2) \\ \\ \Rightarrow\theta=60^o \\ \\ \cos\theta=-(2)/(3) \\ \Rightarrow\theta=131.8^o \end{gathered}`