/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 13 The lengths of two vectors a and... [FREE SOLUTION] | 91Ó°ÊÓ

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The lengths of two vectors a and \(b\) and the angle \(\theta\) between them are given. Find the length of their cross product, \(|\mathbf{a} \times \mathbf{b}|\). $$|\mathbf{a}|=6, \quad|\mathbf{b}|=\frac{1}{2}, \quad \theta=60^{\circ}$$

Short Answer

Expert verified
The magnitude of the cross product is \( \frac{3\sqrt{3}}{2} \).

Step by step solution

01

Understanding Cross Product

The magnitude of the cross product of two vectors \( \mathbf{a} \) and \( \mathbf{b} \) is given by the formula: \[| \mathbf{a} \times \mathbf{b} | = | \mathbf{a} | | \mathbf{b} | \sin(\theta)\]where \( \theta \) is the angle between the two vectors.
02

Substitute Given Values

We are given the following values:- \( |\mathbf{a}| = 6 \)- \( |\mathbf{b}| = \frac{1}{2} \)- \( \theta = 60^{\circ} \)Substitute these into the formula: \[| \mathbf{a} \times \mathbf{b} | = 6 \times \frac{1}{2} \times \sin(60^{\circ})\]
03

Calculate \(\sin(60^{\circ})\)

We know from trigonometry that \( \sin(60^{\circ}) = \frac{\sqrt{3}}{2} \). Substitute this value into the expression.
04

Perform Multiplication

Now, calculate the product:\[6 \times \frac{1}{2} \times \frac{\sqrt{3}}{2} = 6 \times \frac{1}{2} \times \frac{\sqrt{3}}{2} = \frac{6\sqrt{3}}{4} = \frac{3\sqrt{3}}{2}\]
05

Conclude the Magnitude Calculation

The magnitude of the cross product \( |\mathbf{a} \times \mathbf{b}| \) is \( \frac{3\sqrt{3}}{2} \). This is the final result.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Vector Magnitude
Understanding the magnitude of a vector is crucial when working with vector operations. The magnitude of a vector, often represented as \(|\mathbf{a}|\) or \(|\mathbf{b}|\), is a measure of its length.
  • For a vector \(\mathbf{a}\) in two-dimensional space, with components \(a_x\) and \(a_y\), the magnitude is given by \(|\mathbf{a}| = \sqrt{a_x^2 + a_y^2}\).
  • In three-dimensional space, if a vector \(\mathbf{a}\) has components \(a_x\), \(a_y\), and \(a_z\), the magnitude becomes \(|\mathbf{a}| = \sqrt{a_x^2 + a_y^2 + a_z^2}\).
The magnitude tells us how long the vector is in the coordinate system. It does not give us information about direction. In the given problem, the magnitudes of vectors \(\mathbf{a}\) and \(\mathbf{b}\) are 6 and \(\frac{1}{2}\) respectively. This sets the stage for further calculations.
Angle Between Vectors
Finding the angle between two vectors helps in understanding their spatial relationship. This angle, often denoted as \(\theta\), can significantly influence the result of vector operations such as the cross product.The angle between vectors \(\mathbf{a}\) and \(\mathbf{b}\) is used in the cross product formula: \(| \mathbf{a} \times \mathbf{b} | = | \mathbf{a} | | \mathbf{b} | \sin(\theta)\). The angle impacts how much of one vector moves perpendicularly towards another.
  • If the angle is \(0^{\circ}\), the vectors are pointing in the same direction and their cross product is zero because there is no perpendicular component.
  • If the angle is \(90^{\circ}\), the vectors are at a perfect right angle to each other, maximizing the cross product.
In our problem, the angle \(\theta = 60^{\circ}\) contributes a factor of \(\sin(60^{\circ}) = \frac{\sqrt{3}}{2}\) in the cross product calculation.
Trigonometric Functions
Trigonometric functions like sine, cosine, and tangent are pivotal in vector mathematics.Sine Function:The sine function relates an angle in a right triangle to the ratio of the opposite side over the hypotenuse. Within the context of vectors, the sine function helps determine the magnitude of the perpendicular component.For an angle \(\theta\):- \(\sin(\theta) = \text{opposite side} / \text{hypotenuse}\) - For a \(60^{\circ}\) angle, this results in \(\sin(60^{\circ}) = \frac{\sqrt{3}}{2}\).This trigonometric function plays a critical role in our vector cross product formula. It scales the product of the magnitudes of the two vectors based on how "twisted" they are relative to each other. Since vectors \(\mathbf{a}\) and \(\mathbf{b}\) form a \(60^{\circ}\) angle, the sine of this angle crucially defines the proportion of their interaction perpendicular to each other.

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Most popular questions from this chapter

Find the area of the parallelogram determined by the given vectors. $$\mathbf{u}=2 \mathbf{i}-\mathbf{j}+4 \mathbf{k}, \quad \mathbf{v}=\frac{1}{2} \mathbf{i}+2 \mathbf{j}-\frac{3}{2} \mathbf{k}$$

An object located at the origin in a three-dimensional coordinate system is held in equilibrium by four forces. One has magnitude 7 Ib and points in the direction of the positive \(x\) -axis, so it is represented by the vector 7 i. The second has magnitude 24 Ib and points in the direction of the positive \(y\) -axis. The third has magnitude 25 Ib and points in the direction of the negative z-axis. (a) Use the fact that the four forces are in equilibrium (that is, their sum is 0 ) to find the fourth force. Express it in terms of the unit vectors \(\mathbf{i}, \mathbf{j},\) and \(\mathbf{k}\) (b) What is the magnitude of the fourth force?

Every line can be described by infinitely many different sets of parametric equations, since any point on the line and any vector parallel to the line can be used to construct the equations. But how can we tell whether two sets of parametric equations represent the same line? Consider the following two sets of parametric equations: Line \(1: \quad x=1-t, \quad y=3 t, \quad z=-6+5 t\) Line \(2: \quad x=-1+2 t, \quad y=6-6 t, \quad z=4-10 t\) (a) Find two points that lie on Line 1 by setting \(t=0\) and \(t=1\) in its parametric equations. Then show that these points also lie on Line 2 by finding two values of the parameter that give these points when substituted into the parametric equations for Line 2 . (b) Show that the following two lines are not the same by finding a point on Line 3 and then showing that it does not lie on Line 4 Line \(3: \quad x=4 t, \quad y=3-6 t, \quad z=-5+2 t\) Line \(4: \quad x=8-2 t, \quad y=-9+3 t, \quad z=6-t\)

Given three vectors \(\mathbf{u}, \mathbf{v},\) and \(\mathbf{w},\) their scalar triple product can be performed in six different orders: $$\begin{array}{lll} \mathbf{u} \cdot(\mathbf{v} \times \mathbf{w}), & \mathbf{u} \cdot(\mathbf{w} \times \mathbf{v}), & \mathbf{v} \cdot(\mathbf{u} \times \mathbf{w}) \\ \mathbf{v} \cdot(\mathbf{w} \times \mathbf{u}), & \mathbf{w} \cdot(\mathbf{u} \times \mathbf{v}), & \mathbf{w} \cdot(\mathbf{v} \times \mathbf{u}) \end{array}$$ (a) Calculate each of these six triple products for the vectors: $$\mathbf{u}=\langle 0,1,1\rangle, \quad \mathbf{v}=\langle 1,0,1\rangle, \quad \mathbf{w}=\langle 1,1,0\rangle$$ (b) On the basis of your observations in part (a), make a conjecture about the relationships between these six triple products. (c) Prove the conjecture you made in part (b).

Two vectors \(u\) and \(v\) are given. Find the angle (expressed in degrees) between \(\mathbf{u}\) and \(v\) $$\mathbf{u}=\langle 2,-2,-1\rangle, \quad \mathbf{v}=\langle 1,2,2\rangle$$

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