i need help in this problem!

[big daddy]

hi everyone,
this is my question u

up.x333x.com/uploads/3d3e4fe53e.jpg

In the circle O, chords AC and BD intersect at K. Find DC given that:

KA = 2x + 1
KB = 3x – 1
AB = 2x + 2
KC = 5x + 2
KD = 5x – 2
i tried to slove it but i did not know where to start

i tried to set the sides to zero and got nothing..

i need your help guys please!

[HallsofIvy]

This is the theorem you need:
"Given a point P in the interior of a circle, pass two lines through P that intersect the circle in points A and D and, respectively, B and C. Then AP·DP = BP·CP."
(I found it by googling on "intersecting chords".)

In your case that says that (5x+2)(2x+1)= (5x-2)(3x-1). Multiply it out and solve the quadratic equation.