Question 246382
Find all solutions of the equation in the interval [0,2π) algebraically. 
Sec^2 x - sec x =2 
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It's a quadratic in sec(x).
sec^2 - sec - 2 = 0
(sec - 2)*(sec + 1) = 0
sec(x) = 2
sec(x) = -1
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sec(x) = 2
x = 60º, 120º = pi/3, 2pi/3
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sec(x) = -1
x = 180º = pi radians