Chapter 13: Problem 33
Find and \(|\) ar when \(r=1, s=-1\) if \(w=(x+y+z)^{2}\) \(x=r-s, y=\cos (r+s), z=\sin (r+s)\)
Short Answer
Expert verified
The value of \(|w|\) is 9.
Step by step solution
01
Define the values of given variables
We begin by identifying the given values for the variables. From the problem, we know that \( r = 1 \) and \( s = -1 \). These will be used in our subsequent calculations.
02
Substitute values into expressions for x, y, z
Substitute the values of \( r \) and \( s \) into the expressions for \( x \), \( y \), and \( z \). This gives: \( x = r - s = 1 - (-1) = 2 \), \( y = \cos(r+s) = \cos(1 + (-1)) = \cos(0) = 1 \), and \( z = \sin(r+s) = \sin(1 + (-1)) = \sin(0) = 0 \).
03
Substitute expressions into the formula for w
Now, substitute the values of \( x \), \( y \), and \( z \) into the formula \( w = (x + y + z)^{2} \). This results in \( w = (2 + 1 + 0)^{2} = 3^{2} = 9 \).
04
Calculate |a| and |w|
We need to calculate the magnitude of the values. The length \(|a|\) is equivalent to \(|w|\) since \(w\) itself represents the magnitude in this context. Therefore, \(|w| = 9\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Algebra
Algebra is a branch of mathematics that uses variables to represent numbers in equations and expressions. In this problem, we are using algebra to manipulate given expressions with substitutions. Let's break this down:
Hence, algebra's role is crucial in breaking down the problem into manageable calculations. Always start by assigning values properly and performing operations step-by-step.
- We have expressions involving variables: \( x = r-s \), \( y = \cos(r+s) \), and \( z = \sin(r+s) \).
- Given \( r = 1 \) and \( s = -1 \), algebra allows us to substitute these values into our expressions directly.
- Substituting \( r \) and \( s \) means calculating \( x = 1 - (-1) = 2 \), which is a straightforward algebraic operation using substitution and simplification.
Hence, algebra's role is crucial in breaking down the problem into manageable calculations. Always start by assigning values properly and performing operations step-by-step.
Trigonometry
Trigonometry is the study of angles and the relationships between the lengths and angles of triangles. In this exercise, trigonometry helps calculate values of \( y \) and \( z \) using standard trigonometric functions: cosine and sine.
- We use \( y = \cos(r+s) \), which simplifies to \( \cos(0) \) since \( r+s = 1+(-1)=0 \).
- The cosine of zero degrees or radians, \( \cos(0) \), is equal to 1. Similarly, \( z = \sin(r+s) \) simplifies to \( \sin(0) \).
Functions
Functions play a central role in calculus and algebra. They offer a way to describe relationships between varying quantities. In this example, the function \( w=(x+y+z)^2 \) tells how \( w \) changes based on inputs \( x \), \( y \), and \( z \).
- Functions let us substitute specific input values, enabling calculation of outputs — here we calculated \( w \) using determined values.
- With \( x = 2 \), \( y = 1 \), and \( z = 0 \), we find \( w = (2 + 1 + 0)^2 \), simplifying to \( 3^2 = 9 \).