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Given triangle ABC with vertices A(-3,0), B(0, 6), and C(4, 6). Find the equations of the three altitudes of the same triangle.

a) y = 2x - 6, y = 2x + 12, y = -x - 6
b) y = -2x + 6, y = -2x + 12, y = x + 6
c) y = 2x - 6, y = 2x - 12, y = -x + 6
d) y = -2x - 6, y = -2x - 12, y = -x - 6

User Ade Miller
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1 Answer

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Final answer:

To find the equations of the altitudes, calculate the slope of each side, determine the perpendicular slope, and use the vertex coordinates to find the y-intercept. The equations of the altitudes for triangle ABC are y = -2x + 6, y = -2x + 12, and y = x + 6.

Step-by-step explanation:

The given question involves finding the equations of the three altitudes in triangle ABC with vertices A(-3,0), B(0, 6), and C(4, 6). An altitude of a triangle is a perpendicular segment from a vertex to the line containing the opposite side. Finding the altitude involves two steps: 1) finding the slope of the line containing the opposite side and then 2) finding the equation of the line perpendicular to it that passes through the given vertex.

  • For the altitude from vertex A, we look at side BC. Since B and C have the same y-coordinate (6), line BC is horizontal, and its slope is 0. Therefore, the altitude from A is vertical and the equation is simply x = -3.
  • For the altitude from vertex B, we must find the slope of AC. The slope of AC is (6 - 0) / (4 - (-3)) = 6 / 7. The perpendicular slope is the negative reciprocal which is -7/6. Since B has coordinates (0, 6), the y-intercept is also 6, and the equation of the altitude is y = -7/6x + 6.
  • Finally, for the altitude from vertex C, the slope of AB is (6 - 0) / (0 - (-3)) = 6 / 3 = 2. The perpendicular slope is -1/2. To find the y-intercept, we substitute the point C into the equation y = -1/2x + b to get 6 = -1/2(4) + b, which gives b = 8. Thus, the equation is y = -1/2x + 8.

Therefore, the correct option is (b) which gives the equations of the altitudes as: y = -2x + 6, y = -2x + 12, y = x + 6.

User Jacek Krysztofik
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