9514 1404 393
Answer:
x = 6
Explanation:
The angle bisector divides the triangle proportionally. Here, the top segment on each half is double the length of the bottom one, (8 = 2·4), so ...
x = 2·3
x = 6
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If you like, you can write that as a proportion:
x/3 = 8/4
x = 3(8/4) = 3·2 . . . . . multiply by 3 to get x by itself
x = 6