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Write an equation for the trigonometric function below and explain your thinking in identifying the equation.​

Write an equation for the trigonometric function below and explain your thinking in-example-1

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Answer: f(x) = 0.5*sec(x)

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Step-by-step explanation:

The graphs for secant and cosecant are disconnected sets of "parabolic" curves. I put it in quotes because those aren't really parabolas even if they might look it.

If we plugged x = 0 into y = csc(x), then you'll find that y = undefined. This is due to a division by zero error.

  • csc(x) = 1/sin(x)
  • If x = 0, then sin(x) = 0 and csc(x) = 1/0 = undefined

This basically rules out csc(x) because the given graph clearly shows x = 0 is in the domain.

Luckily sec(x) works when x = 0. It leads to y = 1

  • sec(x) = 1/cos(x)
  • If x = 0, then cos(x) = 1 and sec(x) = 1/1 = 1

In other words, the point (0,1) is on the curve y = sec(x).

If the function was f(x) = 0.5sec(x) then f(0) = 0.5 to match the graph.

I recommend using either GeoGebra or Desmos as a graphing tool. Both can handle the trig functions mentioned. Make sure you adjust the x-axis scale to include things like pi/2, pi, 3pi/2, etc.

User Nicholas Koskowski
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