Answer:
a. 5 units
b. 5 units
Step-by-step explanation:
Given:
The path the dolphin Travels can be modelled by
where h represents the height of the dolphin and d represents horizontal distance.
To find: maximum height that the dolphin reaches and the distance covered by dolphin
Solution:

Differentiate with respect to 

To find the critical point, put 

Differentiate
again with respect to 

So,
is a point of maxima

a. 5 units
b. 5 units