In the adjoining fig. In a circle with centre C and chord DE ,ahe CF perpendicular to chord DE.If diameter of a circle is 20cm and DE=16cm,then CF=?GIVE REASON

DC=CF
We know
[tex]\boxed{\sf L=\dfrac{\theta}{180}\times πr}[/tex]
[tex]\\ \large\sf\longmapsto L=\dfrac{90}{180}\times \dfrac{22}{7}\times 10[/tex]
[tex]\\ \large\sf\longmapsto L=\dfrac{1}{2}\times \dfrac{220}{7}[/tex]
[tex]\\ \large\sf\longmapsto L=\dfrac{110}{7}[/tex]
[tex]\\ \large\sf\longmapsto L=15.5[/tex]
Now
[tex]\\ \large\sf\longmapsto CF=L+r-DE[/tex]
[tex]\\ \large\sf\longmapsto CF=15.7+10-16[/tex]
[tex]\\ \large\sf\longmapsto CF=25.7-16[/tex]
[tex]\\ \large\sf\longmapsto CF=9.7cm[/tex]
[tex]\large\sf\red{⟼L=18090×722×10}[/tex]
[tex]\begin{gathered}\\ \large\sf\red{ ⟼ L=\dfrac{1}{2}\times \dfrac{220}{7}}\end{gathered}[/tex]
[tex]\begin{gathered}{ \large\sf\red{⟼ L=\dfrac{110}{7}}\end{gathered}[/tex]
⟼ L=15.5
Now
⟼ CF=L+r−DE
⟼ CF=15.7+10−16
⟼ CF=25.7−16