Answer:
9
Step-by-step explanation:
Compare your x2 + y2=81 to the following:
x^2 + y^2 = 81
The " ^ " symbol indicates exponentiation.
Now compare x^2 + y^2 = 81 to
x^2 + y^2 = r^2.
This is the standard equation of a circle of radius r centered at the origin, (0,0). You can see for yourself that 81 must equal r^2.
Taking the square root of 81, we get plus or minus 9.
But the radius must be positive, so we reject the -9 and take +9.
The radius is 9.
Take the area of the small photograph and divide it by four, assuming it's a square, each side would then be 6 inches. The large photograph has double the side length of the small one, so 6 multiplied by 2 is 12. To find the area of the large (square) photograph, multiply 12 by 12 as two of the sides, and the area of the large photo is 144 square inches
