Answer:
a. Not perpendicular.
b. Perpendicular.
Explanation:
We need to check whether the segments through the origin and the points listed perpendicular.
Product of slopes of two perpendicular lines is -1.

(a) The given points are (9,10) and (10,9).
Slope of line segment through (0,0) and (9,10) is

Slope of line segment through (0,0) and (10,9) is

Product of slopes is

Therefore, the line segments through the origin and the points (9,10) and (10,9) are not perpendicular.
(b) The given points are (9,6) and (4,-6).
Slope of line segment through (0,0) and (9,6) is

Slope of line segment through (0,0) and (4,-6) is

Product of slopes is

Therefore, the line segments through the origin and the points (9,6) and (4,-6) are perpendicular.