Question 224522
ln(cosx)=-1


First "undo" the ln by raising both sides as a power of e.


{{{e^(ln(cosx))=e^-1}}}
{{{cosx=e^-1}}}


Next, undo the cos function by using the arccos function:
{{{x= arccos (e^-1)}}}


Using a calculator, I got 68.42 degrees.  If the calculator is in radian mode, I got 1.19 radians.


R^2