we can see the line measuring 5 bisects both sides and this makes it a midsegment.

The Triangle Midsegment Theorem states that

A midsegment connecting two sides of a triangle is parallel to the third side and is half as long.

Therefore,

x= 2(5) = 10

in problem 12

since the line measuring 5 bisects one of the sides and its length is half the line marked 10. we can conclude that it is a midsegment and it follows that it bisects the third side. Hence,

x = 4

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