Question

The sum of the areas of two circles is 8pie square meters. Find the length of a radius of each circle ifone of them is twice as long as the other.what is the radius of the larger circle?

Answer 1

nice

area=pir^2
the areas are
pir^2+pi(2r)^2
they add to 8pi

8pi=pir^2+pi(2r)^2
undistribute pi
8pi=pi(r^2+(2r)^2)
divide both sides by pi
8=r^2+(2r)^2
expand
8=r^2+4r^2
add
8=5r^2
divide by 5
8/5=r^2
sqrt both sides
√(8/5)=r
double since it is double
2√(8/5) is radius of bigger aka (4√10)/5

radius=(4√10)/5