At which points would the river be traveling the slowest?

This would be traveling at the lower reaches.

Explanation:

A river would be traveling the fastest at the upper reaches and it becomes slower at the middle reaches and the slowest at the lower reaches. A place where water flows fast in a river is where the width is narrow and the bottom is steep. (This is just examples incase you would like to keep notes).

the working equation for the angular size is the product of the physical size and 360 degrees divided by the product of two pi and distance from earth. the minimum size would be 0.559 degrees while the maximum size would be 0.49 degrees.