Answer:
The answer is "[tex]216\ ft^2[/tex]"
Step-by-step explanation:
Please find the graph file in the attachment.
The area of its tree house's outsides of the square walls and triangular ceilings is equivalent to four squares with four triangles,
[tex]\to A=4[(6)^2+\frac{1}{2} (6)(6)]\\\\[/tex]
[tex]=4[36+\frac{1}{2} (36)]\\\\=4[36+18]\\\\=4[ 54]\\\\=216\ ft^2[/tex]
