A circle whose area is 4 has a radius of x. Find the area of a circle whose radius is 3x.
3 answers
The answer is 28.26
The answer is 36.
The formula for area is A = pi*r^2.
Plug in 4 for the area and r for the radius
4 = pi*r^2
divide by pi
4/pi = r^2
Find the square root of both numbers. r = 2/radical pi
Then solve a new equation for area
pi*(3r)^2 = Area
plug in 2/radical pi for r.
3*2/radical pi = 6/radical pi
square that and cancel out the radical
36/pi*pi = A
cancel pi
36 = A
Reasoning: When you multiply the radius by 3 you are multiplying the area by 9 because you square the radius so when the radius is x then it's 3x and when you square it it becomes 9x
The formula for area is A = pi*r^2.
Plug in 4 for the area and r for the radius
4 = pi*r^2
divide by pi
4/pi = r^2
Find the square root of both numbers. r = 2/radical pi
Then solve a new equation for area
pi*(3r)^2 = Area
plug in 2/radical pi for r.
3*2/radical pi = 6/radical pi
square that and cancel out the radical
36/pi*pi = A
cancel pi
36 = A
Reasoning: When you multiply the radius by 3 you are multiplying the area by 9 because you square the radius so when the radius is x then it's 3x and when you square it it becomes 9x
36 is the area