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Ch. 3 - Radian Measure and The Unit Circle
Lial - Trigonometry 12th Edition
Lial12th EditionTrigonometryISBN: 9780136552161Not the one you use?Change textbook
Chapter 4, Problem 61

Find the approximate value of s, to four decimal places, in the interval [0, π/2] that makes each statement true.


tan s = 0.2126

Verified step by step guidance
1
Identify the given equation: \(\tan s = 0.2126\), where \(s\) is in the interval \([0, \frac{\pi}{2}]\).
Recall that to find \(s\), you need to use the inverse tangent function (also called arctangent), which is written as \(\arctan\) or \(\tan^{-1}\).
Apply the inverse tangent to both sides of the equation to isolate \(s\): \(s = \arctan(0.2126)\).
Use a calculator set to radians mode to find the approximate value of \(s\) by evaluating \(\arctan(0.2126)\).
Round the result to four decimal places to get the final approximate value of \(s\) within the interval \([0, \frac{\pi}{2}]\).

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Understanding the Tangent Function

The tangent function relates an angle in a right triangle to the ratio of the opposite side over the adjacent side. It is periodic and defined for all angles except where cosine is zero. Knowing how to interpret tan s = 0.2126 helps in finding the angle s whose tangent value matches this ratio.
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Introduction to Tangent Graph

Inverse Tangent (Arctan) Function

The inverse tangent function, denoted arctan or tan⁻¹, is used to find the angle whose tangent is a given number. Since tan s = 0.2126, s = arctan(0.2126) gives the angle in radians. This function returns values typically in the interval (-π/2, π/2), which includes the given domain [0, π/2].
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Radian Measure and Interval Constraints

Angles can be measured in radians, where π radians equal 180 degrees. The problem restricts s to the interval [0, π/2], meaning s is between 0 and 90 degrees. Understanding this interval ensures the correct solution is chosen, especially since tangent is positive and increasing in this range.
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