Motion in a plane

For any arbitrary motion in space, which of the following relations are true :
(a) vaverage
= (1/2) (v (t
1
) + v (t
2
))
(b) v
average
= [r(t
2
) – r(t
1
) ] /(t
2
– t
1
)
(c) v (t) = v (0) + a t
(d) r (t) = r (0) + v (0) t + (1/2) a t
2
(e) a average
=[ v (t
2
) – v (t
1
)] /( t
2
– t
1
)
(The ‘average’ stands for average of the quantity over the time interval t
1
to t
2
)