Equation:
[tex]\cos ^2(x)=1[/tex]
To determine if the given value is a solution, we have to replace the given value of x in the equation as follows:
[tex]\cos ^2(\frac{5\pi}{6})=1[/tex]
Using a calculator configurated in radians we get that:
[tex]\cos ^2(\frac{5\pi}{6})=\frac{3}{4}[/tex]
As 1 ≠ 3/4, then x is not a solution.
Answer: x is not a solution.
