Chapter 10: Problem 54
In Exercises 51-58, find the distance between the point and the line. \(\textit{Point}\) \((-2, 1)\) \(\textit{Line}\) \(x - y = 2\)
Short Answer
Expert verified
The shortest distance from the point (-2, 1) to the line \(x - y - 2 = 0\) is \(2.5 \sqrt{2}\).
Step by step solution
01
Rewriting the line equation into standard form
The given line equation is \(x - y = 2\). We can rewrite it into standard form \(Ax + By + C = 0\) by subtracting \(x\) from both sides. This gives us \(x - y - 2 = 0\). Therefore, \(A = 1\), \(B = -1\) and \(C = -2\).
02
Identify the coordinates of the point
The given point is \(-2, 1\), which means \(x = -2\) and \(y = 1\).
03
Calculate the distance
The formula for the distance between a point and a line is:\[\frac{|Ax + By + C|}{\sqrt{A^2 + B^2}}\]Inserting the known values yields:\[\frac{|(1)(-2) + (-1)(1) + (-2)|}{\sqrt{(1)^2 + (-1)^2}} \]which simplifies to:\[\frac{|-2 - 1 - 2|}{\sqrt{1^2 + (-1)^2}} = \frac{5}{\sqrt{2}} = 2.5 \sqrt{2}\]
04
Interpretation of the result
We find that the shortest distance from the point \(-2, 1\) to the line \(x - y - 2 = 0\) is \(2.5 \sqrt{2}\). This is a positive value, indicating that the point and line do not coincide and the point is not on the line.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Distance formula
The distance formula is a mathematical equation used to determine the distance between two points in a plane. It relies on the Pythagorean theorem and is given by the formula: \[d = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}\]Here,
- \((x_1, y_1)\) and \((x_2, y_2)\) are the coordinates of the two points.
- This formula calculates the straight-line distance or 'as-the-crow-flies' distance between them.
Point-line distance
Finding the distance between a point and a line in coordinate geometry requires a specific formula that adapts the concept of perpendicularity. The shortest distance from a point to a line is always the perpendicular distance. The formula to find this distance is:\[\frac{|Ax + By + C|}{\sqrt{A^2 + B^2}}\]where:
- \((x, y)\) are the coordinates of the point.
- \(Ax + By + C = 0\) is the standard form of the line equation.
- \(A\), \(B\), and \(C\) are coefficients from the line equation.
Linear equations
Linear equations consist of terms that are either constants or the product of a constant and a single variable. They are foundational in mathematics as they describe straight lines in geometry. The general form of a linear equation is:\[Ax + By + C = 0\]where:
- \(A\), \(B\), and \(C\) are constants.
- \(x\) and \(y\) represent variables or coordinates on a plane.
Coordinate geometry
Coordinate geometry, also known as analytic geometry, combines algebraic equations with geometric interpretations using a coordinate plane. It provides methods to describe geometric figures using algebra, which offers a way to solve geometric problems numerically.The coordinate plane is defined by two perpendicular axes:
- The horizontal axis (often called the x-axis)
- The vertical axis (often called the y-axis)