To have a right angle the lines need to be perpendicular. That means the slopes are negative recipricals (NR).
We need to find the slope of
(0,10) and (8,5)
M = (10 - 5)/(0 - 8) = -5/8, NR = 8/5
to the slope of
(8,5) and (3,2)
M = (5 - 2)/(8 - 3) = 3/5, NR = -5/3
(0,10) and (3,2)
M = (10 - 2)/(0 - 3) = -8/3, NR = 3/8
There is not a right angle.