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

1 Answer
bp
Nov 16, 2015

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.

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