how do you find the exact value of each expression of sec 7pi/6
sec (7pi/6) = 1 / cos(7pi/6) = 1/cos(210°) = 1/ [-sqrt(3)/2] = -2/sqrt(3)
Remember that 210° is a 30° reference angle in the 3rd quadrant and cos(30°) = sqrt(3)/2.....but the cos is negative in the 3rd quadrant........
