Answer:
24
Explanation:
that means the 2 given angles must be in the same sequence, abd the best is to imagine the second triangle to be oriented in the same way as the first by twisting and turning is so that both marked angles are in the same place as in the first triangle.
and so we see that
A corresponds to D.
B corresponds to F.
C corresponds to E.
and that means that AC corresponds to DE.
AB corresponds to DF.
BC corresponds to FE.
since 2 angles are the same, so is the third (as the sum of all angles in a triangle is always 180°).
and that makes both triangles "similar".
that again means that there is one common scaling factor for all sides from one triangle to the other.
and so, as AC relates to DE, we know 6 is related to 18.
6 × f = 18
f = 18/6 = 3
and therefore, with the same factor applied
DF = AB × f = 8 × 3 = 24