Respuesta :

Answer:

[tex]\boxed{r=3}[/tex]

Step-by-step explanation:

We can use SAS ≅ SAS congruence to validate that the triangles are similar (both share the same side, have another congruent side, and have a congruent angle).

Because the sides are congruent, set them equal to each other and solve for r.

18 - 2r = 4r

18 = 6r

3 = r ⇒ [tex]\boxed{\bold r = 3}[/tex]

Therefore, the answer is D.

Answer:

r = 3

Step-by-step explanation:

Here Triangle ALR is divided precisely in half by the vertical side LU.  The two triangles thus formed are therefore congruent.

Thus, 18 - 2r = 4r, and 6r = 18.  Then r = 3.