What is the orthocenter of a triangle with corners at (2 ,3 )(2,3), (5 ,1 )(5,1), and (9 ,6 )#?

1 Answer
Oct 17, 2016

The Orthocenter is (121/23, 9/23)(12123,923)

Explanation:

Find the equation of the line that goes through the point (2,3)(2,3) and is perpendicular to the line through the other two points:

y - 3 = (9 - 5)/(1 -6)(x - 2)y3=9516(x2)

y - 3 = (4)/(-5)(x - 2)y3=45(x2)

y - 3 = -4/5x + 8/5y3=45x+85

y = -4/5x + 23/5y=45x+235

Find the equation of the line that goes through the point (9,6)(9,6) and is perpendicular to the line through the other two points:

y - 6 = (5 - 2)/(3 - 1)(x - 9)y6=5231(x9)

y - 6 = (3)/(2)(x - 9)y6=32(x9)

y - 6 = 3/2x - 27/2y6=32x272

y = 3/2x - 15/2y=32x152

The orthocenter is at the intersection of these two lines:

y = -4/5x + 23/5y=45x+235
y = 3/2x - 15/2y=32x152

Because y = y, we set the right sides equal and solve for the x coordinate:

3/2x - 15/2 = -4/5x + 23/532x152=45x+235

Multiply by 2:

3x - 15 = -8/5x + 46/53x15=85x+465

Multiply by 5

15x - 75 = -8x + 4615x75=8x+46

23x = + 12123x=+121

#x = 121/23

y = 3/2(121/23) - 15/2y=32(12123)152

y = 3/2(121/23) - 15/2y=32(12123)152

y = 363/46 - 345/46y=3634634546

y = 9/23y=923

The Orthocenter is (121/23, 9/23)(12123,923)