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Ch. 7 - Transcendental Functions
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077Non è quello che usi tu?Cambia libro di testo
Capitolo 7, Problema 7.6.1a

Use reference triangles in an appropriate quadrant to find the angles in Exercises 1–8.
1. a. arctan 1

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Recall that \( \arctan(x) \) is the inverse tangent function, which gives the angle \( \theta \) whose tangent is \( x \). So, we want to find \( \theta \) such that \( \tan(\theta) = 1 \).
Identify the reference angle by considering the positive value 1 for tangent. Since \( \tan(\theta) = \frac{\text{opposite}}{\text{adjacent}} \), a ratio of 1 means the opposite and adjacent sides of the reference triangle are equal.
Recognize that the angle with tangent 1 in the first quadrant is \( \frac{\pi}{4} \) radians (or 45 degrees), because in a right triangle with equal legs, the angles opposite those legs are equal.
Since the problem does not specify a quadrant other than the principal value range of \( \arctan \), which is \( \left(-\frac{\pi}{2}, \frac{\pi}{2}\right) \), the angle is simply the reference angle \( \frac{\pi}{4} \).
Therefore, the solution is \( \theta = \arctan(1) = \frac{\pi}{4} \), using the reference triangle in the first quadrant.

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