Answer: 16 square units
Step-by-step explanation:
let the vertex in quadrant I be (x,y)
then the vertex in quadratnt II is (-x,y)
base of the rectangle = 2x
height of the rectangle = y
Area = xy
= x(12 - x²)
= -x³ + 12x
d(area)/dx = 3x² - 12 = 0 for a maximum of area
3x² = 12
x² = 4
x = ±2
y = 12-4 = 8
So, the largest area = 2 x 8 = 16 square units