Answer :

AlWaleed
Euclidean geometry assumes a flat plane. 
So triangles for example add up to 180 degrees. 

Non-Euclidean geometry is on curved surfaces. 
So triangles on a sphere do not add up to 180 degrees.
Put simple, Euclidean geometry assumes a flat plane. 
So triangles for example add up to 180 degrees. 

Non-Euclidean geometry is on curved surfaces. 
So triangles on a sphere do not add up to 180 degrees.

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