Chapter 6: Problem 65
Use an addition or subtraction formula to find the solutions of the equation that are in the interval \([0, \pi)\). $$\tan 2 t+\tan t=1-\tan 2 t \tan t$$
Short Answer
Expert verified
Solutions: \( t = 0, \frac{\pi}{3}, \frac{2\pi}{3} \).
Step by step solution
01
Write Down the Given Equation
The given equation is: \( \tan(2t) + \tan(t) = 1 - \tan(2t) \tan(t) \). We need to solve this equation using addition or subtraction formulas.
02
Use the Tangent Addition Formula
Recall the tangent addition formula: \( \tan(a + b) = \frac{\tan(a) + \tan(b)}{1 - \tan(a)\tan(b)} \). Compare this formula to the given equation on the left side and notice that it matches the structure of \( \tan(a+b) \). This suggests setting \( a = b = t \), leading to \( \tan(2t) = \frac{2\tan(t)}{1 - \tan^2(t)} \).
03
Simplify the Equation
Substitute the formula \( \tan(2t) = \frac{2\tan(t)}{1 - \tan^2(t)} \) into the equation \( \tan(2t) + \tan(t) = 1 - \tan(2t) \tan(t) \). Simplify the left side to get \( \frac{2\tan(t)}{1 - \tan^2(t)} + \tan(t) \).
04
Combine and Solve the Equation
Combine \( \frac{2\tan(t)}{1 - \tan^2(t)} + \tan(t) = 1 - \tan(2t)\tan(t) \) into one expression. This simplifies to solving \( \tan(3t) = 0 \) using the angles for which tangent is zero.
05
Find Values for t
Find \( t \) values within the interval \([0, \pi)\) where \( \tan(3t) = 0 \). This happens at \( 3t = n\pi \) where \( n \) is an integer. Solving for \( t \), we have \( t = \frac{n\pi}{3} \). Check for values \( t = 0, \frac{\pi}{3}, \frac{2\pi}{3} \).
06
Confirm Solution Lies in the Interval
Ensure the solutions \( t = 0, \frac{\pi}{3}, \frac{2\pi}{3} \) are within the interval \([0, \pi)\). All these values satisfy the equation given this interval.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Tangent Addition Formula
The tangent addition formula is a powerful tool in trigonometry. It's particularly helpful for simplifying expressions that involve the tangent of sums or differences of angles. The formula is given by:
By setting \( a = t \) and \( b = t \) (thus \( a + b = 2t \)), the formula helps us express \( \tan(2t) \) as a combination of \( \tan(t) \):
- \( \tan(a + b) = \frac{\tan(a) + \tan(b)}{1 - \tan(a)\tan(b)} \).
By setting \( a = t \) and \( b = t \) (thus \( a + b = 2t \)), the formula helps us express \( \tan(2t) \) as a combination of \( \tan(t) \):
- \( \tan(2t) = \frac{2\tan(t)}{1 - \tan^2(t)} \).
Solving Trigonometric Equations
Solving trigonometric equations involves finding the angle values that satisfy a given trigonometric identity. In our case, we started with an equation:
Initially, we applied the tangent addition formula to simplify the left-hand side of the equation. Once simplified, this leads us to new forms of the original equation, focusing primarily on single terms like \( \tan(3t) = 0 \).
To solve \( \tan(3t) = 0 \), we recognize that \( \tan(x) = 0 \) whenever \( x = n\pi \). So, this equation becomes:
- \( \tan(2t) + \tan(t) = 1 - \tan(2t)\tan(t) \).
Initially, we applied the tangent addition formula to simplify the left-hand side of the equation. Once simplified, this leads us to new forms of the original equation, focusing primarily on single terms like \( \tan(3t) = 0 \).
To solve \( \tan(3t) = 0 \), we recognize that \( \tan(x) = 0 \) whenever \( x = n\pi \). So, this equation becomes:
- \( 3t = n\pi \), for integer values of \( n \).
- \( t = \frac{n\pi}{3} \).
Interval Notation
Interval notation is a shorthand used to describe the set of all numbers within a certain interval on the number line. This directive is often used in solving equations to limit the solutions to a specific section of the graph.
In this problem, we focus on the interval \([0, \pi)\), which includes all numbers from 0 up to but not including \( \pi \). When solving \( \tan(3t) = 0 \), we derive a general solution form, \( t = \frac{n\pi}{3} \).
In this problem, we focus on the interval \([0, \pi)\), which includes all numbers from 0 up to but not including \( \pi \). When solving \( \tan(3t) = 0 \), we derive a general solution form, \( t = \frac{n\pi}{3} \).
- By substituting integers for \( n \), we find specific candidate solutions for \( t \).
- Only values of \( t \) that fall within \([0, \pi)\) are valid.
- \( t = 0, \frac{\pi}{3}, \) and \( \frac{2\pi}{3} \) are all solutions found within the interval.