Look at this figure
What can you say about the vertical lines?
Perpendicular Lines
Parallel Lines
Inclined at some angle
Nothing can be concluded.
Lines perpendicular to the same lines are parallel to each other. Hence, the vertical lines are parallel.
With reference to the figure, ABCD is a parallelogram. AE and CF are angle bisectors of ∠DAC and ∠ACB respectively. What can you say about lines AE and CF?
What can you say about the nature of motion of a body if its displacement-time graph is
(a) a straight line parallel to time axis?
(b) a straight line inclined to the time axis with an acute angle?
(c) a straight line inclined to the time axis with an obtuse angle?
(d) a curve?