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Figure 3.9.8(a) contains graphs of (in black) and (in red). The line is a vertical asymptote for both curves, suggesting that as , the difference tends to the indeterminate form .
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Figure 3.9.8(a) also suggests that the values of the functions near are so similar that perhaps the limit of the difference might indeed be zero. Of course, this can be verified immediately in Maple via the calculation
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Figure 3.9.8(a) (black) and (red)
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The difference needs to be rewritten so that as , it tends to the indeterminate form or . The recipe in Table 3.9.2 leads to the same result as that obtained by basic trigonometry, namely,
As , this latter tends to the indeterminate form , which yields to L'Hôpital's rule. The complete calculation would then be