Circles

EasyMediumHard
12345678910111213141516171819202122
Question 4
Medium64%

The circle C C\,C has the equation x2+y2+8x−4y+k=0x^2 + y^2 + 8x - 4y + k = 0x2+y2+8x−4y+k=0 where k k\,k is a constant. Given that the point (1,5)(1, 5)(1,5) lies on CCC.

a.

Find the value of kkk.

[2]
b.

Find the coordinates of the centre and the radius of CCC.

[3]
c.

A straight line that passes through the point A(3,7)A(3, 7)A(3,7) is a tangent to the circle C C\,C at the point BBB. Find the exact length of the line ABABAB.

[5]

Circles Questions

  1. AS Level
  2. /Maths
  3. /Circles