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# Domain of Secant

Sin, cos, tan, cot, sec and cosec are six Trigonometric Functions that we all must be aware of. Sec or Secant is one such functions whose value for angle is equal to multiplicative inverse of its cosine function value, i.e.
Secant(x) = 1 / Cosine(x) or,
Secant(x) * Cosine(x) = 1.
Graphing of Domain of secant function gives us a periodic U – shape plot that continues to repeat this behaviour between moving up and down wave. Domain of secant is symmetric about the y- axis.
Here, angle i.e. “x” we consider will be measured in terms of radians rather than degrees. Draw a vertical line at Point x = (∏ / 2) + (c * ∏) for all integers “c”. Repeat this procedure for all integers by drawing all vertical lines that occur within domain of your graph.
Plot the point (0, 1) such that when it is extended upwards to left and right, it does not touches dotted lines given by x = -∏ / 2 and x = ∏ / 2. This line should make a curvy shape in upward direction; instead of drawing a Straight Line, draw one that follows second half of graphical shape i.e. "U". To understand this shape better, one should go for plotting points such as (∏ / 4, [sq. root 2]). Remember sec(x) = 1 / cos(x).
Between two lines drawn earlier at: x = ∏ / 2 and x = 3 * (∏ / 2), draw a similar shape i.e. U – shape, opening downwards and passing through point (∏, -1). Repeat the shape you drew in previous steps for every (2 * ∏) units. We see that graph of secant cycles infinitely.