D(5, 7), E(4, 3), and F(8, 2) form the vertices of a triangle. What is m∠DEF? A. 30° B. 45° C. 60° D. 90°
1 answer:
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Answer:
a = -0.3575
Step-by-step explanation:
The points A and D lie on the x-axis, this means that they are the x-intercepts of the parabola, and therefore we can find their location.
The points A and B are located where
This gives
Now given the coordinates of A, we are in position to find the coordinates of the point B. Point B must have y coordinate of y=2 (because the base of the trapezoid is at y=0), and the x coordinate of B, looking at the figure, must be x coordinate of A plus horizontal distance between A and B, i.e
Thus the coordinates of B are:
Now this point B lies on the parabola, and therefore it must satisfy the equation
Thus
Therefore
