Question

Equation of a tangent to the circle with centre (2, –1) is 3x + y = 0. The squar  of the length of the tangent to the circle from the point (23, 17) is

Solution

Correct option is

1525

 

Length of the perpendicular from the centre (2, –1) on the tangent  which is the radius of the circle. Equation of the circle is 

         (x – 2)2 + (y + 1)2 = 5/2   

or      2[(x – 2)2 + (y + 1)2] – 5 = 0   

The required length = 2[(23 – 2)2 + (17 + 1)2] – 5 

                                = 2[441 + 324] – 5 = 1525

SIMILAR QUESTIONS

Q1

On the line joining the points A (0, 4) and B (3, 0), a square ABCD is constructed on the side of the line away from the origin. Equation of the circle having centre at C and touching the axis of x is 

Q2

A circle with centre at the origin and radius equal to a meets the axis of x at A and B.P (α) and Q (β) are two points on this circle so that α – β = 2γ, where γ is a constant. The locus of the point of intersection of APand BQ is

Q3

A circle C1 of radius b touches the circle x2 + y2 = a2 externally and has its centre on the positive x-axis; another circle C2 of radius c touches the circle C1 externally and has its centre on the positive x-axis. Given ab < c, then the three circles have a common tangent if abc are in 

Q4

Angle of intersection of these circle is

Q5

If C1C2 are the centre of these circles than area of Δ OC1 C2, where Ois the origin, is

Q6

A triangle has two of its sides along the axes, its third side touches the circle x2 + y2 – 2ax – 2ay + a2 = 0. If he locus of the circumcentre of the triangle passes through the point (38, –37) then a2 – 2a is equal to

Q7

Two circles are inscribed and circumscribes about a square ABCD, length of each side of the square is 32. P and Q are points respectively of these circles, then  is equal to

Q8

Let A be the centre of the circle x2 + y2 – 2x – 4y – 20 = 0. The tangents at the point B(1, 7) and C(4, –2) on the circle meet at the point D. If Δ denotes the area of the quadrilateral ABCD, then 45Δ is equal to

Q9

If four distinct points (2, 3), (0, 2), (4, 5) and (0, t) are concylic, then t3+ 17 is equal to 

Q10

The centres of two circles C1 and C2 each of unit radius are at a distance of 6 units from each other. Let P be the mid-point of the line segment joining the centres of C1 and C2 and C be a circle touching C1 and C2externally. If a common tangent to C1 and C passing through P is also a common tangent to 2 and C1, then the radius of the circle C is