Skip to main content
Ch. 6 - Inverse Circular Functions and Trigonometric Equations
Lial - Trigonometry 12th Edition
Lial12th EditionTrigonometryISBN: 9780136552161Not the one you use?Change textbook
Chapter 7, Problem 19

Find the exact value of each real number y if it exists. Do not use a calculator.
y = arctan 0

Verified step by step guidance
1
Recall that the function \( y = \arctan(x) \) gives the angle \( y \) whose tangent is \( x \), and the range of \( \arctan \) is \( \left(-\frac{\pi}{2}, \frac{\pi}{2}\right) \).
Set up the equation based on the problem: \( y = \arctan(0) \) means \( \tan(y) = 0 \).
Identify all angles \( y \) within the range \( \left(-\frac{\pi}{2}, \frac{\pi}{2}\right) \) where \( \tan(y) = 0 \).
Recall that \( \tan(0) = 0 \), and since \( 0 \) is within the range of \( \arctan \), this is the principal value.
Conclude that the exact value of \( y \) is \( 0 \) because it satisfies \( \tan(y) = 0 \) within the principal range.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Was this helpful?

Key Concepts

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

Definition of the Arctangent Function

The arctangent function, denoted as arctan or tan⁻¹, is the inverse of the tangent function restricted to the interval (-π/2, π/2). It returns the angle whose tangent is the given number, providing a unique output for each real input.
Recommended video:
4:45
How to Use a Calculator for Trig Functions

Tangent Function and Its Values

The tangent of an angle in a right triangle is the ratio of the opposite side to the adjacent side. Key values include tan(0) = 0, which means the angle whose tangent is zero is 0 radians (or 0 degrees). This helps identify the exact value of arctan(0).
Recommended video:
5:08
Sine, Cosine, & Tangent of 30°, 45°, & 60°

Exact Values Without a Calculator

Certain trigonometric values are well-known and can be determined exactly without a calculator, such as arctan(0) = 0. Recognizing these standard angles and their trigonometric ratios is essential for solving problems involving inverse trig functions precisely.
Recommended video:
4:45
How to Use a Calculator for Trig Functions