Chapter 1: Problem 54
Use slopes to show that \(A(-3,-1), B(3,3),\) and \(C(-9,8)\) are vertices of a right triangle.
Short Answer
Expert verified
AB and CA are perpendicular, confirming a right triangle.
Step by step solution
01
Calculate Slope of AB
To find the slope of line segment AB, we need the coordinates of points A and B. The slope formula between two points \((x_1, y_1) \) and \((x_2, y_2) \) is given by \\[ m = \frac{y_2 - y_1}{x_2 - x_1} \]. \Given the coordinates of A(-3, -1) and B(3, 3), the slope of AB is \\[ m_{AB} = \frac{3 - (-1)}{3 - (-3)} = \frac{4}{6} = \frac{2}{3} \].
02
Calculate Slope of BC
Next, we'll find the slope of the line segment BC using the formula for slope. \The coordinates for points B(3, 3) and C(-9, 8) are used here. \\[ m_{BC} = \frac{8 - 3}{-9 - 3} = \frac{5}{-12} = -\frac{5}{12} \].
03
Calculate Slope of CA
Now let's calculate the slope of the line segment CA. Using the points C(-9, 8) and A(-3, -1), the slope is calculated as \\[ m_{CA} = \frac{-1 - 8}{-3 - (-9)} = \frac{-9}{6} = -\frac{3}{2} \].
04
Check for Perpendicular Slopes
In a right triangle, the slopes of two sides must be negative reciprocals if they are perpendicular. We'll check between the pairs of segments: \- The negative reciprocal of \( \frac{2}{3} \) is \( -\frac{3}{2} \). \- The slope \( m_{CA} = -\frac{3}{2} \) matches this reciprocal. \Thus, segments AB and CA are perpendicular.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Slope Calculation
The slope of a line represents its steepness and is calculated using the formula \( m = \frac{y_2 - y_1}{x_2 - x_1} \). This formula uses two points \((x_1, y_1)\) and \((x_2, y_2)\) on the line:
- The numerator \( y_2 - y_1 \) represents the change in the y-values.
- The denominator \( x_2 - x_1 \) is the change in the x-values.
- The fraction \( \frac{\text{change in } y}{\text{change in } x} \) gives the slope.
Perpendicular Lines
Perpendicular lines intersect at a right angle (90 degrees) and a fundamental way to identify them is by examining their slopes. For two lines to be perpendicular, the product of their slopes must equal -1.
- If one line has a slope \( m_1 \), the perpendicular line will have a slope \( m_2 \) such that \( m_1 \times m_2 = -1 \).
- If \( m_1 = \frac{2}{3} \), then the perpendicular slope \( m_2 \) must be \( -\frac{3}{2} \).
Coordinate Geometry
Coordinate geometry uses algebraic techniques to study geometric relationships. This method involves plotting points, lines, and shapes on the Cartesian plane.
- Points are defined by their coordinates \((x, y)\).
- Lines and slopes connect these points mathematically.
- Geometric properties like distances, midpoints, and angles can be calculated.