Question

What are the coordinates of the orthocenter of △XYZ with vertices at X(−3, 3) , Y(1, 3) , and Z(−3, 0) ?

Answer 1

Orthocenter is at (-3,3) The orthocenter of a triangle is the intersection of the three heights of the triangle (a line passing through a vertex of the triangle that's perpendicular to the opposite side from the vertex. Those 3 lines should intersect at the same point and that point may be either inside or outside of the triangle. So, let's calculate the 3 lines (we could get by with just 2 of them, but the 3rd line acts as a nice cross check to make certain we didn't do any mistakes.) Slope XY = (3 - 3)/(-3 - 1) = 0/-4 = 0 Ick. XY is a completely horizontal line and it's perpendicular will be a complete vertical line with a slope of infinity. But that's enough to tell us that the orthocenter will have the same x-coordinate value as vertex Z which is -3. Slope XZ = (3 - 0)/(-3 - (-3)) = 3/0 Another ick. This slope is completely vertical. So the perpendicular will be complete horizontal with a slope of 0 and will have the same y-coordinate value as vertex Y which is 3. So the orthocenter is at (-3,3).