If we draw a perpendicular DP to AB from D. Then PA x PB = PD2.
Here PB = x, then PA = 8 – x.
![](https://www.sarthaks.com/?qa=blob&qa_blobid=15176310183940400489)
x(8 – x) = PD2 , 22 = x2 + PD2
x(8 – x) = 4 – x2 , 8x – x2 = 4 – x2
8x = 4, x = \(\frac{1}{2}\)
Similarly, let us draw a perpendicular CQ to AB from C
AQ = ,PQ = 8 – \((\frac{1}{2}+\frac{1}{2})=7\)
CD = 7cm