Well divide 10.5 by 5 and the answer is there! :D
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Answer:
Rounding it to two decimal places, we get distance, 
Step-by-step explanation:
Given:
The two points are 
The distance between the two points can be obtained using the distance formula which is given as:

Here, for the points, 

Therefore, the distance between the points is:

Rounding it to two decimal places, we get 
All triangles must have angles that add up to the same amount of degrees, so if the two triangles share one exact point, it is assumed that those angles would be the same. Basically just use the fact that the sides are the same and marked by dashes, and the missing line can be proven with the use of the angles that are in between the point that both share.