Don' answer this if you don't know it or you will be reported. concurrency means that two figures or items are exactly the same size and shape. where in life would it be vitally important for two or more items to be congruent?

Well, I guess one example of the importance of concurrency in two objects would be if you were, say, building a chair-and you needed all the legs to be concurrent. If one was not, then the chair might topple over, possibly injuring whomever was sitting on it.
Another example would be if you were duplicating a stuffed animal you sewed so you can sell it. If the stuffed animal was not concurrent to the previous one, then the customer would be dissatisfied. 
I hope this helped :) 

In aeroplanes...if their wings weren't congruent, they wouldn't be able to fly.

Or in the human body... if our limbs weren't congruent, we wouldn't be able to do anything.

Or the planet...if earth's hemispheres weren't congruent, well, I don't think we would even exist.

Hope this helps!