Answer:
The triangle EFG can be constructed with the following specifications:
,
,
,
,
,
.
Step-by-step explanation:
A triangle is formed by either knowing the lengths of its three sides or knowing two angles and the length of a side or knowing a angle and the lengths of two sides. By Geometry, we know that sum of internal angles in triangles equals 180°. In order to construct this triangle, we need to know the measures of angles E, F and G by means of the Law of Cosine:
Angle E
![E = \cos^{-1}\left[\frac{(7\,cm)^{2}-(12\,cm)^{2}-(8\,cm)^{2}}{-2\cdot (12\,cm)\cdot (8\,cm)} \right]](https://tex.z-dn.net/?f=E%20%3D%20%5Ccos%5E%7B-1%7D%5Cleft%5B%5Cfrac%7B%287%5C%2Ccm%29%5E%7B2%7D-%2812%5C%2Ccm%29%5E%7B2%7D-%288%5C%2Ccm%29%5E%7B2%7D%7D%7B-2%5Ccdot%20%2812%5C%2Ccm%29%5Ccdot%20%288%5C%2Ccm%29%7D%20%5Cright%5D)

Angle F
![F = \cos^{-1}\left[\frac{(12\,cm)^{2} - (8\,cm)^{2} - (7\,cm)^{2}}{-2\cdot (8\,cm)\cdot (7\,cm)} \right]](https://tex.z-dn.net/?f=F%20%3D%20%5Ccos%5E%7B-1%7D%5Cleft%5B%5Cfrac%7B%2812%5C%2Ccm%29%5E%7B2%7D%20-%20%288%5C%2Ccm%29%5E%7B2%7D%20-%20%287%5C%2Ccm%29%5E%7B2%7D%7D%7B-2%5Ccdot%20%288%5C%2Ccm%29%5Ccdot%20%287%5C%2Ccm%29%7D%20%5Cright%5D)

Angle G
![G = \cos^{-1}\left[\frac{(8\,cm)^{2}-(12\,cm)^{2}-(7\,cm)^{2}}{-2\cdot (12\,cm)\cdot (7\,cm)} \right]](https://tex.z-dn.net/?f=G%20%3D%20%5Ccos%5E%7B-1%7D%5Cleft%5B%5Cfrac%7B%288%5C%2Ccm%29%5E%7B2%7D-%2812%5C%2Ccm%29%5E%7B2%7D-%287%5C%2Ccm%29%5E%7B2%7D%7D%7B-2%5Ccdot%20%2812%5C%2Ccm%29%5Ccdot%20%287%5C%2Ccm%29%7D%20%5Cright%5D)

The triangle EFG can be constructed with the following specifications:
,
,
,
,
,
.