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# Equations of Lines (Altitudes and Orthocentres)

1. 1
Given a triangle with vertices A(5,1), B(0,-9) and C(-9,3) find:

a) The equation of the altitude from A to BC.
b) The equation of the altitude from C to AB.
c) The orthocentre of the triangle ABC.
2. 2
Given a triangle with vertices A(3,-9), B(-9,0) and C(1,5) find:

a) The equation of the altitude from A to BC.
b) The equation of the altitude from C to AB.
c) The orthocentre of the triangle ABC.
3. 3
Given a triangle with vertices A(-4,3), B(6,8) and C(8,-6) find:

a) The equation of the altitude from A to BC.
b) The equation of the altitude from C to AB.
c) The orthocentre of the triangle ABC.

$$e=mc^2$$