Elitmus
Exam
Numerical Ability
Geometry
a ring having radius 2 units is placed in the corner of a room such that it touches the adjecent walls. if a smaller circle is drawn in between the ring and the corner point of these two walls, what would be the area of such a circle? i dont remember the options...asked in elitmus on 10/07/2016
Read Solution (Total 22)
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- when the circle is touching the wall and radius is 2 unit, then the gap between the circle and wall forms a square with side of 2 unit.... so we have to find the diagonal of the square which is D^2=2^2+2^2 =2.8284.
so if we subtract 2.8284 -2=0.8284 ... the new circle having a diameter of 0.8284 and RADIUS will be 0.4142
by solving we have πr2 =0.53919373
- 8 years agoHelpfull: Yes(8) No(10)
- no one is considering here the gap between peripheri of smaller circle and the corner point...as a matter of fact a circle cant touch corner of a wall unless its radius is zero...means a point. and yeah ...i remebered options too now...
a) root2-1 ...which is indeed 200% wrong coz of ignoring abovesaid distance
b) 3-2*root2 c) 6-4root2 d)7-4root 2
now think again....
- 8 years agoHelpfull: Yes(6) No(0)
- answer will be pi*(6-4root2)^2
- 8 years agoHelpfull: Yes(6) No(1)
- Method1:
Area of circle =4pi, Area of Sector of Circle =pi
Area of square =2*2=4
Area enclosed can be dertemined = Area of Square - area of sector .
Method 2;
Radius of Circle =2
Diameter of Square =2root2
hence diameter of small circle= 2root2- 2=0.82
radius of circle =0.82/2=0.41
hence area of small circle=pi *0.41*0.41=Ans - 8 years agoHelpfull: Yes(5) No(3)
- pi*[root(2)-1]^2
- 8 years agoHelpfull: Yes(4) No(0)
2(root2 - 1)
x= ______________
(1 + root2)- 8 years agoHelpfull: Yes(3) No(3)
- Draw lines from centre of ring to corner lines I.e perpendicular.
Draw a line from centre of smaller circle to radius of bigger ring....
It will be more clear from figure...
Equation will be
(2-x)^2+(2-x)^2=(2+x)^2
Solve u will get 6-4√2 - 8 years agoHelpfull: Yes(2) No(0)
- its devastating my mind
- 8 years agoHelpfull: Yes(1) No(0)
- taking radius os small circle as r. in that case pythagores theorem will be applied where hypotenuse will be (2+r) and other two sides are (2-r) and (2-r) equate both side and solve for r you will get the solution.
- 8 years agoHelpfull: Yes(1) No(1)
- option b is correct
- 8 years agoHelpfull: Yes(1) No(0)
- Let r be the smaller radius and x be the gap between smaller circle and corner. Now,
Length of diagonal of square formed due to bigger circle=2root2
2root2= 2+2r+x (as bigger radius=2)
further, 2(root2 -1)= 2r+x
now apply pythagoras theorem to find the distance between center of smaller circle to corner(r+x).
Here we get, r+x = 2(r^2)
Now we already have 2r+x,
So r+r+x=2(root2 -1)
On simplifying for value of r, we get r=6-4root2 - 7 years agoHelpfull: Yes(1) No(0)
- radius of smaller circle= 2(root2-1)/2= (root2-1)
- 8 years agoHelpfull: Yes(0) No(2)
- sorry....these options are corresponding to radius of smaller circle bt i hv asked area for the same in question....so apologize fr it ...u guys solve it fr radius..
- 8 years agoHelpfull: Yes(0) No(2)
- How did u guys solve it?
- 8 years agoHelpfull: Yes(0) No(0)
- let 'a' be the radius then,
a+a*root(2)=0.828 - 8 years agoHelpfull: Yes(0) No(1)
- In this question how can we find the side of square. There is nothing given for square side . when i found the side of the square then i will solve this question
- 8 years agoHelpfull: Yes(0) No(0)
- radius will be 6-4root2
and area of small circle will be Pi*6-4root2 - 8 years agoHelpfull: Yes(0) No(0)
- let the radius of smaller circle 'r'.
By applying pythagoras theorem we find the gap occur b/w wall &smaller circle [since wall act like tamgent to circle]
rsqrt2+r+2=2sqrt2
by solving this we get r=6-4sqrt2 - 8 years agoHelpfull: Yes(0) No(0)
- distance from corner point to peripheri= 2*root2-2
radius of smaller circle= 2*(root2-1)/root2+1
area =pi*r2 - 8 years agoHelpfull: Yes(0) No(0)
- π4((3-2√2)/(3+2√2))
- 7 years agoHelpfull: Yes(0) No(0)
- radius is 3-2root(2)
area is {17-12root(2)}*3.14 - 7 years agoHelpfull: Yes(0) No(0)
- let dia of smaller circle be =d
length of diagonal from the centre of the bigger circle to the corner of the wall= sqrt(8).
distance from the corner to the tip of smaller circle = a.
using similarity,
2/sqrt(8)=d/2/(d/2+a).......(2)
a = sqrt(8) - d - 2...............(1)
solving the eqn. we will get the value of d, and hence the area. - 6 years agoHelpfull: Yes(0) No(0)
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