Question

the area of of the ring between two cincretic circles is 3186cm2. Find the raddi of the two circlesif (a) the sum is 42 and (b) the difference is 35​

Answer 1

Answer:

Let two radius are 'x' and 'y', so,

x+y=42....(1)

and 

x−y=28.....(2)

Now adding (1) and (2), we get

2x=70

x=35

Putting in (1)

35+y=42

y=7

Therefore, radius of two concentric circles are 35 cm and 7 cm.