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#### A-level C3 Chapter 6 Trig Help

Given sec(x) = k, |k| ≥ 1 and that x is obtuse, express in terms of k: cosec(x). The textbook answer is with the negative but I don't understand why. I have consider the CAST diagram and understand cosec(x) is positive for and obtuse x value. This would mean I take the negative root for x is negative but for x is positive, shouldn't it be the positive root. I've managed to get the answer: +/- k/√(k^2 - 1). My question is how do I know whether to write the answer with the positive root or the negative root. I've managed to get the answer: +/- k/√(k^2 - 1). My question is how do I know whether to write the answer with the positive root or the negative root. Source: The Student Room

#### AS level Trig

The equation tan x = 4cos x has two roots in the interval x is greater than or equal to -180 degrees and x is less than or equal to 180 degrees. Question: Sketch , on a single diagram showing values of x from -180 degrees to +180 degrees, the graphs of y=tanx and y=4csx. These are denoted by A and B where a is less than B. Show A and B on your sketch and express B in terms of A. Question: Sketch , on a single diagram showing values of x from -180 degrees to +180 degrees, the graphs of y=tanx and y=4csx. Source: The Student Room

#### A-level Connected particles

(a) the tension in the string. | - R ---------> P N. | b -. |-. B. It is given that when P = 14, AR = 0. 4 m, BR = 0. 3 m and the perpendicular distance of R from the vertical line AB is 0. 24 m. Find:. The ends of the string are attached to fixed points A and B , where A is vertically above B. A horizontal force of magnitude P N acts on R. The system is in equilibrium with the string taut. AR makes an angle a with the downward vertical and BR makes an angle b with the upward vertical (see diagram below). Source: The Student Room