Question

How do you use a calculator to solve each equation on the interval `(0 <= x < 2pi)` for `sec(x) = - 4`?

Answer 1

x= 104.47 and 255.52 degrees

Explanation:

Sec x= -4 means cos x =`(-1)/4`. x would thus lie in 2nd and 3rd quadrant. Now get the solution for cos x= `1/4` using inverse function key. This gives x= 75.52degrees, which is the angle in 1st quadrant. For cos x = `(-1)/4`, x would be in 2nd or 3rd quadrant. x would thus be 180-75.52= 104.47 degrees in the second quadrant. x value for third quadrant would be 180+75.52= 255.52 degrees.