Chapter 4: Problem 46
Graph each line. Construct a perpendicular segment through the given point. Then find the distance from the point to the line. $$y=x+2,(2,-2)$$
Short Answer
Expert verified
The distance from the point (2,-2) to the line y = x + 2 is \( 3\sqrt{2} \).
Step by step solution
01
Graph the Line
Start by graphing the line given by the equation \( y = x + 2 \). This is a linear equation in slope-intercept form, \( y = mx + b \), where \( m = 1 \) is the slope and \( b = 2 \) is the y-intercept. **Plot the y-intercept (0,2)** on the coordinate plane.Using the slope 1, move up 1 unit and to the right 1 unit to plot another point. Connect these points with a straight line.
02
Identify the Perpendicular Slope
To find the slope of a line that is perpendicular to the original line, use the negative reciprocal of the original slope. The original slope is 1, so the negative reciprocal is \( -1 \).
03
Equation of the Perpendicular Line
Use the point-slope form of a line equation \( y - y_1 = m(x - x_1) \), where \( (x_1, y_1) = (2, -2) \) and the slope \( m = -1 \). Substituting these values gives:\[ y + 2 = -1(x - 2) \]Simplify this equation to find the line equation:\[ y = -x + 0 \]
04
Graph the Perpendicular Line
Graph the line \( y = -x \) using the point \( (2, -2) \). From this point, use the slope \( -1 \) (move down 1 unit and to the right 1 unit, or up 1 unit and to the left 1 unit to plot another point). Draw the line through these points, ensuring it crosses the original line at a right angle.
05
Find Intersection Point
Find the intersection of the line \( y = x + 2 \) and the perpendicular line \( y = -x \). Set the equations equal to find the x-coordinate:\[ x + 2 = -x \]Solve for \( x \):\[ 2x = -2 \rightarrow x = -1 \]Substitute \( x = -1 \) back into one of the original equations to find \( y \):\[ y = -(-1) = 1 \]Thus, the intersection point is \( (-1, 1) \).
06
Calculate the Distance
Use the distance formula to find the distance from the point \( (2, -2) \) to the intersection point \( (-1, 1) \):\[ d = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2} \]Substitute \( (x_1, y_1) = (2, -2) \) and \( (x_2, y_2) = (-1, 1) \):\[ d = \sqrt{(-1 - 2)^2 + (1 + 2)^2} = \sqrt{(-3)^2 + 3^2} = \sqrt{9 + 9} = \sqrt{18} = 3\sqrt{2} \].
07
State the Distance
The distance from the point \( (2, -2) \) to the line \( y = x + 2 \) is \( 3\sqrt{2} \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Slope-Intercept Form
The slope-intercept form is a common way to express the equation of a straight line. It is given by the formula: \[ y = mx + b \]. Here, \( m \) stands for the slope of the line, while \( b \) represents the y-intercept. This form is very handy because it directly tells us how to graph the line.
- Start at the y-intercept \((0, b)\).
- Then, use the slope \( m \) to plot further points. If \( m \) is 1, it indicates that for every unit you move to the right on the x-axis, you also move up by 1 unit on the y-axis. This creates a 45-degree diagonal line.
Distance Formula
In coordinate geometry, the distance formula is used to calculate the distance between two points on a plane. The formula is derived from the Pythagorean theorem and is: \[ d = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2} \].
- \((x_1, y_1)\) and \((x_2, y_2)\) are the coordinates of the two points.
- This formula ensures that you can find the straight-line distance irrespective of the alignment of the points.
Point-Slope Form
The point-slope form is especially useful for writing the equation of a line when you know one point on the line and its slope. The general expression of the point-slope form is: \[ y - y_1 = m(x - x_1) \], where:
- \((x_1, y_1)\) is a known point on the line.
- \( m \) represents the slope.
Coordinate Geometry
Coordinate Geometry involves using algebraic principles to understand geometric concepts on a coordinate plane. This branch of geometry allows us to visualize geometrical shapes using numbers and equations.
- The fundamental elements include points, lines, and planes, which are translated into coordinates and algebraic equations.
- It enables us to find slopes, distances, midpoints, and areas.