Answer:
Short leg = 6.
Step-by-step explanation:
Hypotenuse = 2x
short leg = x
long leg = x√3
Hypotenuse = 2x=12
x = 12/2
x=6
short leg = x = 6
Area: 312
Perimeter: 75
Area is l·w
20·16=320
two corners aren't filled
320-9-9=318
Add all the sides for perimeter
17+3+3+13+20+13+3+3=75
Answer: height of the pyramid is 52 m.