Chapter 9: Problem 29
The coordinates of the vertices of \(\triangle J K L\) are \(J(-3,4), K(0,5),\) and \(L(5,10)\). CAN'T COPY THE GRAPH Graph the image of \(\triangle J K L\) after a reflection in \(x=2\) and one in \(x=6\)
Short Answer
Expert verified
The vertices after reflections are J''(5,4), K''(8,5), L''(3,10).
Step by step solution
01
Understand the Concept of Reflection
When a point is reflected over a line, its image is equidistant from the line on the opposite side. In this problem, we are reflecting the triangle first over the line \(x=2\) and then over the line \(x=6\). The reflection process involves finding the new coordinates of each vertex after these reflections.
02
Reflect Over x=2 Line
Reflect each vertex over the x=2 line:\(-3\) to the left of 2, J's reflection is at \((-3)+(2-(-3)) \rightarrow x = 7\): J' is at (7, 4).\(0\) reflecting across 2 is found by \(2x - 0 = 2 \rightarrow K' \, will be \, (4, 5)\).Reflect L \(5\) across 2, \(2x - 5 = 2 \rightarrow x = -1\), L' is (9,10). These are the vertices of the image after the first reflection, J'(7,4), K'(4,5), L'(9,10).
03
Reflect Over x=6 Line
Reflect each vertex from Step 2 over the line \(x=6\):J' is 7 and reflecting over 6, calculate New J: 2x -7 = 6, so x' = 5K' is 4, reflect over 6: 2x-4 = 6, x'=8.Reflecting L' is 9, reflect over 6, using 2x -9 = 6 x'=3.Hence the final vertices after both reflections are J''=(5,4), K''=(8,5), L''=(3,10).
04
Plot the Image
Plot the original triangle \(J(-3,4), K(0,5), L(5,10)\) and the new triangle \(J''(5,4), K''(8,5), L''(3,10)\) on a coordinate plane. Use the line x=2 and x=6 to help visualize the reflections.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Reflection
In coordinate geometry, reflection is a kind of transformation that flips a shape over a line, creating a mirror image. This line, called the "line of reflection," acts as the mirror. To reflect a point over a line, you need to determine its distance from the line and place it equally far on the opposite side. In our exercise, \triangle JKL\ is reflected over the lines \(x=2\) and \(x=6\).
- For the first reflection over \(x=2\), each vertex's x-coordinate changes based on its distance from the line. If a vertex is at \(x=a\) and the line of reflection is \(x=b\), the reflected x-coordinate is \(2b-a\).
- The same process applies for reflection over \(x=6\) using the coordinates after the first reflection.
Graphing
Graphing in coordinate geometry involves plotting points on a coordinate plane to form various shapes, like triangles. Each point has an x-coordinate and a y-coordinate. When graphing, it's crucial to place each point correctly based on these coordinates.
- To graph a triangle, plot each of its vertices on the coordinate plane and connect them with straight lines.
- For example, in our exercise, the original triangle \( \triangle J K L \) has vertices \((-3,4)\), \((0,5)\), and \((5,10)\).
- After reflecting these vertices, new points are plotted to show the triangle's new position.
Vertices
Vertices are the corner points of geometric shapes. In our triangle \(\triangle J K L\), the vertices are \(J(-3,4)\), \(K(0,5)\), and \(L(5,10)\). These points define the shape and size of the triangle.
- A vertex is a crucial reference point in transformations like reflection and rotations.
- In our exercise, each of these vertices shifts positions after each reflection to new coordinates.
Coordinate Plane
The coordinate plane is a two-dimensional surface for graphing points, lines, and shapes. It consists of two axes: the horizontal x-axis and the vertical y-axis. The intersection of these axes is the origin, \((0,0)\). Each point on this plane is identified by a pair of coordinates, \((x,y)\).
- In our exercise, we plot the original and reflected positions of \(\triangle J K L \) on this plane.
- The lines \(x=2\) and \(x=6\) are vertical on the coordinate plane and serve as mirrors for the reflections.
- Understanding how to plot and read points on this plane is vital for visualizing geometric transformations.