Home
Class 12
MATHS
Three circles with radius r(1), r(2), r(...

Three circles with radius `r_(1), r_(2), r_(3)` touch one another externally. The tangents at their point of contact meet at a point whose distance from a point of contact is `2`. The value of `((r_(1)r_(2)r_(3))/(r_(1)+r_(2)+r_(3)))` is equal to

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we will follow the steps outlined in the video transcript, ensuring we derive the required expression step by step. ### Step-by-Step Solution: 1. **Understanding the Configuration**: We have three circles with radii \( r_1, r_2, r_3 \) that touch each other externally. The points of contact form a triangle with vertices at the centers of the circles. 2. **Identifying the Distances**: The distances between the centers of the circles are: - Distance between Circle 1 and Circle 2: \( r_1 + r_2 \) - Distance between Circle 1 and Circle 3: \( r_1 + r_3 \) - Distance between Circle 2 and Circle 3: \( r_2 + r_3 \) 3. **Setting Up the Triangle**: Let the points of contact be \( A, B, C \) corresponding to circles with radii \( r_1, r_2, r_3 \) respectively. The triangle formed by these points is denoted as triangle \( ABC \). 4. **Incenter and Radius**: The tangents at the points of contact meet at a point \( O \) (the incenter of triangle \( ABC \)), and the distance from \( O \) to any side of the triangle is given as 2. This means the inradius \( r \) of triangle \( ABC \) is 2. 5. **Calculating the Semi-perimeter**: The semi-perimeter \( s \) of triangle \( ABC \) is given by: \[ s = \frac{(r_2 + r_3) + (r_1 + r_3) + (r_1 + r_2)}{2} = r_1 + r_2 + r_3 \] 6. **Area of Triangle**: The area \( \Delta \) of triangle \( ABC \) can be expressed using the inradius: \[ \Delta = r \cdot s = 2 \cdot (r_1 + r_2 + r_3) \] 7. **Using Heron's Formula**: According to Heron's formula, the area can also be expressed as: \[ \Delta = \sqrt{s(s - (r_2 + r_3))(s - (r_1 + r_3))(s - (r_1 + r_2))} \] Substituting the values: \[ \Delta = \sqrt{(r_1 + r_2 + r_3)(r_1)(r_2)(r_3)} \] 8. **Equating the Two Area Expressions**: Setting the two expressions for area equal gives: \[ 2(r_1 + r_2 + r_3) = \sqrt{(r_1 + r_2 + r_3)(r_1)(r_2)(r_3)} \] 9. **Squaring Both Sides**: Squaring both sides results in: \[ 4(r_1 + r_2 + r_3)^2 = (r_1 + r_2 + r_3)(r_1)(r_2)(r_3) \] 10. **Dividing by \( (r_1 + r_2 + r_3) \)**: Assuming \( r_1 + r_2 + r_3 \neq 0 \), we can divide both sides by \( (r_1 + r_2 + r_3) \): \[ 4(r_1 + r_2 + r_3) = (r_1)(r_2)(r_3) \] 11. **Rearranging the Equation**: Rearranging gives: \[ \frac{(r_1)(r_2)(r_3)}{(r_1 + r_2 + r_3)} = 4 \] ### Final Result: Thus, the value of the expression \( \frac{r_1 r_2 r_3}{r_1 + r_2 + r_3} \) is equal to **4**.

To solve the problem, we will follow the steps outlined in the video transcript, ensuring we derive the required expression step by step. ### Step-by-Step Solution: 1. **Understanding the Configuration**: We have three circles with radii \( r_1, r_2, r_3 \) that touch each other externally. The points of contact form a triangle with vertices at the centers of the circles. 2. **Identifying the Distances**: ...
Promotional Banner

Topper's Solved these Questions

  • TEST PAPERS

    RESONANCE ENGLISH|Exercise PART : 1MATHEMATICS SEC - 1|1 Videos
  • TEST PAPERS

    RESONANCE ENGLISH|Exercise PART : 1MATHEMATICS|9 Videos
  • TEST PAPER

    RESONANCE ENGLISH|Exercise MATHEMATICS|48 Videos
  • TEST SERIES

    RESONANCE ENGLISH|Exercise MATHEMATICS|132 Videos

Similar Questions

Explore conceptually related problems

(r_(2)+r_(3))sqrt((r r_(1))/(r_(2)r_(3)))=

In an equilateral triangle with usual notations the value of (27r^(2)R)/(r_(1)r_(2)r_(3)) is equal to

In any triangle, the minimum value of r_(1) r_(2) r_(3) //r^(3) is equal to

Value of 1/(r_(1)^2)'+ 1/(r_(2)^2)+ 1/(r_(3)^2)+ 1/(r_()^2) is :

The value of 1/(r_(1)^(2))+1/(r_(2)^(2))+1/(r_(2)^(3))+1/(r^(2)) , is

Two circles of radii r_(1) and r_(2), r_(1) gt r_(2) ge2 touch each other externally. If theta be the angle between the direct common tangents, then,

Two fixed circles with radii r_1 and r_2,(r_1> r_2) , respectively, touch each other externally. Then identify the locus of the point of intersection of their direction common tangents.

value of the expression (b-c)/(r_(1))+(c-a)/r_(2)+(a-b)/r_(3) is equal to

Find the points of contact Q and R of a tangent from the point P(2,3) on the parabola y^2=4xdot

Find the points of contact Q and R of a tangent from the point P(2,3) on the parabola y^2=4xdot

RESONANCE ENGLISH-TEST PAPERS-MATHEMATICS
  1. Three circles with radius r(1), r(2), r(3) touch one another externall...

    Text Solution

    |

  2. The least positive vlaue of the parameter 'a' for which there exist at...

    Text Solution

    |

  3. The locus of the midpoint of a chord of the circle x^2+y^2=4 which sub...

    Text Solution

    |

  4. If f(x)=x + tan x and f si the inverse of g, then g'(x) equals

    Text Solution

    |

  5. Tangents PA and PB are drawn to parabola y^(2)=4x from any arbitrary p...

    Text Solution

    |

  6. If lim(nrarroo) (n.2^(n))/(n(3x-4)^(n)+n.2^(n+1)+2^(n))=1/2 where "n" ...

    Text Solution

    |

  7. Eccentricity of ellipse 2(x-y+1)^(2)+3(x+y+2)^(2)=5 is

    Text Solution

    |

  8. If (tan^(-1)x)^(3)+(tan^(-1)y)^(3)=1-3tan^(-1)x.tan^(-1)y. Then which ...

    Text Solution

    |

  9. If f:RrarrR is a continuous function satisfying f(0)=1 and f(2x)-f(x)=...

    Text Solution

    |

  10. tan^(-1)(sinx)=sin^(-1)(tanx) holds true for

    Text Solution

    |

  11. The function f(x) = (x^(2) - 1)|x^(2) - 3x + 3|+cos (|x|) is not diffe...

    Text Solution

    |

  12. Consider parabola P(1)-=y=x^(2) and P(2)-=y^(2)=-8x and the line L-=lx...

    Text Solution

    |

  13. If the normals at (x(i),y(i)) i=1,2,3,4 to the rectangular hyperbola x...

    Text Solution

    |

  14. Let f(x) = x^(3) - x^(2) + x + 1 and g(x) = {{:(max f(t)",", 0 le t le...

    Text Solution

    |

  15. The sum of the roots of the equation tan^(-1)(x+3)-tan^(-1)(x-3)="sin"...

    Text Solution

    |

  16. For an ellipse having major and minor axis along x and y axes respecti...

    Text Solution

    |

  17. If f:[0,1]rarrR is defined as f(x)={(x^(3)(1-x)"sin"1/(x^(2)) 0ltxle1)...

    Text Solution

    |

  18. If f(x)=root (3)(8x^(3)+mx^(2))-nx such that lim(xrarroo)f(x)=1 then

    Text Solution

    |

  19. For the curve y=4x^3-2x^5, find all the points at which the tangents p...

    Text Solution

    |

  20. Minimum value of (sin^(-1)x)^(2)+(cos^(-1)x)^(2) is greater than

    Text Solution

    |

  21. If y + b = m(1)(x + a) and y + b = m(2)(x+a) are two tangents to the p...

    Text Solution

    |