Question 397907
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Hi, previously posted.
{{{drawing(400,400,-2,10,-2,10,grid(1),
line(0,0,4,8), locate(0,0,A), locate(4,8,B), locate(6,2,C), 
line(4,8,6,2), line(6,2,0,0), circle(2,4,0.2),locate(2,4,D), 
line(6,2,2,4),
graph (400,400,-2,10,-2,10))}}} 
A. Show that triangle ABC is an isosceles triangle
B(4,8) and C(6,2)                       A(0,0) and C(6,2)
distance AB = {{{sqrt( (-2)^2 + 6^2)}}}= distance AC = {{{sqrt(6^2 +(2)^2 )}}}

B. Find the coordinates of D , the midpoint of the base AB
A(0,0) and B(4,8)
Midpoint({{{(x[1] + x[2])/2}}}, {{{(y[1] + y[2])/2}}}) (4/2,8/2) OR PT(2,4)

C. Show that CD is perpendicular to AB
 m of CD = {{{(4-2) /( 2-6) = 2/-4 = -1/2}}}
 m of AB = 8/4 = 2
 SLOPES negative reciprocals, lines perpendicular