Answer:
this is a required answer.
Answer:
The answer to your question is (x - 7)² + y² = 81
Step-by-step explanation:
Data
Center = (7, 0)
radius = 9
Process
To find the standard equation of a circle, just substitute the values of the center and the radius.
Standar equation of a circle
(x - h)² + (y - k)² = r²
-Identify the values of h and k
h = 7 k = 0 and r = 9
-Substitution
(x - 7)² + (y - 0)² = 9²
-Simplification
(x - 7)² + y² = 81
93/5 turned into a decimal is 18.6
Dr /dt = 7
A = pi r^2
dA / dr = 2pir
dA/dt = dA/dr * dr/dt = 2pir * 7 = 14pir
when r = 12 rate of change of the area = 14*pi*12 = 168pi
= 527.79 cm^2 / minute to nearest hundredth