Help with finding the Altitude of a triangle?

Question

The vertices of triangle ABC are A(8,5),B(0,1), and C(9,-2) Find an equation of the altitude from A to line BC. Please explain, Thanks = )

Answer 1

slope of line BC, m = (- 2 - 1)/(9 - 0) = - 1/3

slope of altitude (at right angle) m1 = - 1/m = 3

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equ of altitude >> passes from A (8,5) with slope = m1

y - 5 = 3[x - 8]

y - 3x + 19 =0