Question

How many solutions are there in the interval 0 11 years ago

Answer 1

\[\cos(2x)=-1\]
\[2x=\cos ^{-1}(-1)\]
\[x=\frac{ \cos ^{-1}(-1) }{ 2 }\]
solve for x

Answer 2

whenever cos(2x)=-1 is when there will be a solution

Answer 3

this only happens one time within to interval [0,2(pi)]