Answer:
CD = 16.5
Step-by-step explanation:
To find the distance between two points, use this formula: 
point C can be info set 1: (10, -1) x₁ = 10 y₁ = -1
point D can be info set 2: (-6, 3) x₂ = -6 y₂ = 3
Substitute the information into the formula

Simplify inside each bracket
Square the numbers
Add inside the root
Enter into calculator
Rounded to the nearest tenth, the first decimal
The distance CD is 16.5.
The base is a square, therefore all the sides of the base are the same. This also means all the triangles have the same area.
10*10 = 100 cm^2 for the base
0.5*10*12 = 60 cm^2 for each triangle
100 + 4(60) = 340 cm^2
Concave up is U-shaped.
There will be a inflection/critical point f'(x) =0 then a negative slope f'(x) = neg then another inflection/critical point f'(x) =0 at the bottom of the U-shape then a positive slope to last inflection/critical point. The interval for the Concave Up shape is the first and last inflection points.