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Which of the following angles is in the solution set of sec^2θ - 3secθ - 2 = 0 for 0° ≤ θ < 360°.
A. 0°
B. 56°
C. 60°
D. 74°

Answer :

1 / cos^2 O - 3 / cos O - 2 = 0
1 - 3 cos O -  2 cos^2 O = 0

2 cos^2 O + 3 cos O - 1 = 0

cos O = 0.2807 , -1.78   ( -1.78 cannot be a solution)

O = 74 degrees  (from  0.2807) another solution is 360-74 =  286 degrees

Its D

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