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Find parametric equations for the line. The line through the point (-4,2,3) and parallel to a line in the \(y z\) -plane which makes a \(45^{\circ}\) angle with the positive \(y\) -axis and the positive \(z\) -axis.

Short Answer

Expert verified
Parametric equations: \( x = -4 \), \( y = 2 + \frac{\sqrt{2}}{2}t \), \( z = 3 + \frac{\sqrt{2}}{2}t \).

Step by step solution

01

Understand the Direction in the yz-plane

Since the line makes a 45° angle with both the positive y and z axes, we construct a direction vector in the yz-plane. Recall that the cosine of 45° is \( \frac{\sqrt{2}}{2} \). The direction vector parallel to the yz-plane is \( \mathbf{d}_{yz} = (0, \frac{\sqrt{2}}{2}, \frac{\sqrt{2}}{2}) \).
02

Apply the Direction to 3D

Since the direction of the line should be parallel to the yz-plane with no x-component, the full direction vector in 3D is \( \mathbf{d} = (0, \frac{\sqrt{2}}{2}, \frac{\sqrt{2}}{2}) \).
03

Set an Initial Point and Construct Parametric Equations

Given point on the line is P(-4, 2, 3). The parametric equations of the line use this point and the direction vector:\[ x = -4 \]\[ y = 2 + \frac{\sqrt{2}}{2}t \]\[ z = 3 + \frac{\sqrt{2}}{2}t \] where \( t \) is a parameter.

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Key Concepts

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

Direction Vectors
Direction vectors are essential in defining the orientation of a line or a line segment in space. They are often used in geometry and physics to describe motion and orientation. A direction vector essentially tells us which way the line is pointing.

In our scenario, a line is specified to be parallel to the yz-plane and also makes a 45° angle with both the positive y-axis and z-axis. To develop a direction vector, we analyze the components along each axis:
  • If a line is parallel to the yz-plane, its x-component is zero. This tells us that there is no movement along the x-axis.
  • Both the y- and z-components are equal when measured at a 45° angle to their respective axes, due to the symmetry of this angle. The cosine of 45° is \( \frac{\sqrt{2}}{2} \), giving us a vector of \((0, \frac{\sqrt{2}}{2}, \frac{\sqrt{2}}{2})\).
This direction vector describes the orientation of our line in 3D space with clarity and precision.
Angles in Geometry
Angles are a fundamental concept in geometry, defining the rotation needed to align one direction with another. They are crucial in establishing orientation and constructing direction vectors.

When a problem states a line makes a specific angle with the axes, it implies a particular direction of orienting the vector components. In our exercise, the line forms a 45° angle with both the y-axis and the z-axis. This specific angle helps in understanding the transformation of coordinate components into vectors:
  • A 45° angle means the y- and z-components of the vector must be equivalent due to equal cosine values, i.e., \( \cos(45°) = \frac{\sqrt{2}}{2} \).
  • Such angles lead us to create symmetric and balanced vector components when orienting our direction vector in the yz-plane.
These geometric concepts of angles provide the foundation for creating precisely oriented lines in any dimensional space.
3D Coordinate Geometry
In 3D coordinate geometry, every point and line has a clear position in space through coordinates and direction vectors. It's a mathematical language used to describe points and lines in space spanning across three dimensions (x, y, and z).

Our exercise requested the construction of a line moving through a specific point, \((-4, 2, 3)\). Incorporating the direction from the yz-plane, we define its path using parametric equations:
  • The starting point is denoted by our coordinates \((-4, 2, 3)\). This acts as a reference or anchor from which the direction vector projects.
  • The direction vector \((0, \frac{\sqrt{2}}{2}, \frac{\sqrt{2}}{2})\) advances us along the line constantly as we increase or decrease the parameter \(t\).
Thus, we form the parametric equations:
- \( x = -4 \)
- \( y = 2 + \frac{\sqrt{2}}{2}t \)
- \( z = 3 + \frac{\sqrt{2}}{2}t \)
Each equation describes movement along its respective axis, based on the direction taken from a given point in 3D space.

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