Why do many scientists work in groups? a.
To generate new ideas
c.
Because it is too expensive to work on their own
b.
To make sure that the work is accurate
d.
So there is always someone in lab to monitor experiments

I well say to make sure that the work is accurate

Explanation:

I hope this is right

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. 

it doesn't. it was imagined up in the middle ages.