Question

Circle 1, Circle 2, and Circle 3 have the same center and have radii, respectively, of r₁ cm, r₂ cm, r₃ cm, where r₁ < r₂ < r₃. Let A₁ be the area of Circle 1, let A₂ be the area of the region within Circle 2 and outside Circle 1, and let A₃ be the area of the region within Circle 3 and outside Circle 2, where all areas are in cm². What are the values of \small \frac{A_{1}}{A_{2}} and \small \frac{A_{2}}{A_{3}} ?
(1) A₂ = A₃
(2) A₂+A₃ = 2 A₁

Answer 1

Answer:

a) A₁ /A₂  =  r₁² / (r₂²   - r₁²)

b) A₂ /A₃  = (r₂²   - r₁²) / (r₃²   - r₂²)

Step-by-step explanation:

We have Circle 1  and area  A₁  

Area of circle 2 outside circle 1     =  A₂

Area of circle 3 outside circle 2    = A₃

On the other hand we have

A₁  = π*r₁²   area of circle 1

A₂´ =  π*r₂² area of circle 2

A₃´ = π*r₃²  area of circle 3

All areas in cm²

a) A₁ /A₂        

A₁  =  π*r₁²

According to problem statement  A₂  = π*r₂²  -   A₁

A₂  =  π*r₂²  -   π*r₁²      ⇒         A₂  =  π* (r₂²   - r₁²)

Then  A₁ /A₂  =   π*r₁² / [π* (r₂²   - r₁²)]

A₁ /A₂  =  r₁² / (r₂²   - r₁²)

b)  A₂ /A₃        

A₂  =   π* (r₂²   - r₁²)

And

A₃   =  π* (r₃²   - r₂²)

Therefore

A₂ /A₃  =   π* (r₂²   - r₁²) / π* (r₃²   - r₂²)  ⇒  A₂ /A₃  = (r₂²   - r₁²) / (r₃²   - r₂²)

A₂ /A₃  = (r₂²   - r₁²) / (r₃²   - r₂²)