The reason is using point slope formula.
The photo attached given below:
<h3>what is point slope formula?</h3>
The equation of a straight line in the form y − y1 = m(x − x1) where m is the slope of the line and (x1, y1) are the coordinates of a given point on the line — compare slope-intercept form.
Now, we have to find the slope of AE, BF and CD.
We have to done this with help of coordinates.
So, we have to use point slope formula to find the slope of AE, BF and CD.
Learn more about this concept here:
brainly.com/question/2810340
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