Answer
The triangle in the figure 4 is correct .
Reason
by using the trignometric identity
![tan\theta = (Perpendicular)/(Base)](https://img.qammunity.org/2019/formulas/mathematics/high-school/h5afpp5hy2wlsipxotjdvp4u61pb1c6998.png)
Thus
![tan 30^(\circ) = (Perpendicular)/(Base)](https://img.qammunity.org/2019/formulas/mathematics/high-school/mapqkf5qhe4oyec9arc9qmymqyd8np2t8h.png)
![tan 30 ^(\circ) =(1)/(√(3))](https://img.qammunity.org/2019/formulas/mathematics/high-school/1kzj4qk2h8b583q42kqk28ntpzpagnz87x.png)
Now in the figure (1)
![tan 30^(\circ) = (13.9)/(8)](https://img.qammunity.org/2019/formulas/mathematics/high-school/cohj2oi5h2zqry8azwwwu24t2cwamtedj5.png)
![(1)/(√(3)) = (13.9)/(8)](https://img.qammunity.org/2019/formulas/mathematics/high-school/vceuuzjoq7m0ubprqt3ephv2rcdcysqfpl.png)
on simplify
![0.5774 \\eq 1.7375](https://img.qammunity.org/2019/formulas/mathematics/high-school/82nagel3zjv5hoh06q5pagi3ybxmbksy2w.png)
thus side length measures in the figure (1) is not correct .
Now in the figure (2)
![tan30^(\circ) =(16)/(8) \\ (1)/(√(3)) =(16)/(8) \\ 0.577 \\eq 2](https://img.qammunity.org/2019/formulas/mathematics/high-school/fhucws5v4l3hnnvza62dqgmtcpxrt9e751.png)
thus side length measures in the figure (2) is not correct .
Now in the figure (3)
![tan 30 ^(\circ) = (8)/(16) \\ (1)/(√(3)) =(8)/(16) \\ 0.577\\eq0.5](https://img.qammunity.org/2019/formulas/mathematics/high-school/5l2esw72icdq35khpi976l3dkjzhwlz8jx.png)
thus side length measures in the figure (3) is not correct .
Now in the figure (4)
![tan30^(\circ) = (8)/(13.9) \\ (1)/(√(3)) =(8)/(13.9)\\ 0.577 = 0.576(approx)](https://img.qammunity.org/2019/formulas/mathematics/high-school/mp0wq06pgdk8qamdvlsxudfv6y63qe12d7.png)
Therefore the figure (4) is correct triangle has side length measures that could be correct
Hence proved