Answer:
Matt ;
Used diameter of the ball instead of Radius
Step-by-step explanation:
The volume of a sphere is given as :
4/3πr³
Radius, r = diameter / 2
Given that, the diameter = 15 cm ; The Radius = 15 / 2 = 7.5 cm
Matt made an error in his calculation by failing to covert the value of the diameter given to Radius.
By dividing the diameter by 2 = 15 / 2 = 7.5, we obtain the Radius, which is what Billy did in her own calculation.
Answer:
16π ≈ 50.27 square units
Step-by-step explanation:
The equation is that of a circle of radius 4. The area of a circle is given by ...
A = πr²
A = π(4²) = 16π ≈ 50.27 . . . . square units
_____
The equation can be put into the standard form for a circle to find its radius.
(x^2 -2x) +(y^2 +6y) = 6 . . . . collect variable terms on the left
(x^2 -2x +1) +(y^2 +6y +9) = 6 + 1 + 9 = 16 . . . . . complete the squares
(x -1)^2 +(y +3)^2 = 4^2 . . . . . the radius is 4
Compare to the form ...
(x -h)^2 +(y -k)^2 = r^2 . . . . circle of radius r centered at (h, k)
