circles

Q. Of the two concentric circles the smaller one has the equation x2+y2=4. If each of the two intercepts on the line x+y=2 made between the two circles is 1, find the equation of the larger circle.

just want the answer

8 Answers

13
Avik ·

Thnx b555....another method....

Line intersects Bigger Circle @ X(p,q) & smaller one @ A(0,2) & B(2,0).....

Take Line XAB ; use section formula

0 = 1*2 + 2√2p => p=-1/√2
2= 2√2q/(1+2√2) => q= 2+1/√2

Radius = √(p2+q2) = √(5+2√2)

13
Avik ·

am getting its radius = 2+ 4√2

106
Asish Mahapatra ·

hmm the answers given radius = √5+2√2 and i got the radius to be 2+1/√2

13
Avik ·

U did using figure kya ??? Similarity of triangles ?.....i found my fault ;trying another way....

39
Dr.House ·

solution:

u get the points on smaller corcle and on line as (2,0) and(0,2)

now let the points on line as well as bigger circle be (x1,y1) and (x2,y2)

now use the fact that

(2-x1)2+(-y1)2=1

x1+y1=2 to get x1 and y1

now use x12+y12=k2 where k is radius u get k as √(5+2√2)

here i have assumed the point towards (2,0) side is(x1,y1)

hope u get it

13
Avik ·

Got it.....1 min.....

39
Dr.House ·

nice method; ultimately u find coordinates of a point on bigger circle

106
Asish Mahapatra ·

thx both of u

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