4. In the diagram shown, a metal support brace is added to stabilize a metal
triangle. The brace is parallel to the 18-foot base of the triangle and divides the
left side into a 4-foot and a 6-foot section. What is the length of the metal
support brace?
4 ft
6 ft
18 ft
A 7.2 ft
B 12 ft
C 27 ft
D 8.5 ft