Question

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​

Answer 1

DC=CF

• Diameter=20cm
• Radius=20/2=10cm

We know

`\boxed{\sf L=(\theta)/(180)* πr}`

`\\ \large\sf\longmapsto L=(90)/(180)* (22)/(7)* 10`

`\\ \large\sf\longmapsto L=(1)/(2)* (220)/(7)`

`\\ \large\sf\longmapsto L=(110)/(7)`

`\\ \large\sf\longmapsto L=15.5`

Now

`\\ \large\sf\longmapsto CF=L+r-DE`

`\\ \large\sf\longmapsto CF=15.7+10-16`

`\\ \large\sf\longmapsto CF=25.7-16`

`\\ \large\sf\longmapsto CF=9.7cm`

Answer 2

`\large\sf\red{⟼L=18090×722×10}`

`\begin{gathered}\\ \large\sf\red{ ⟼ L=(1)/(2)* (220)/(7)}\end{gathered}`

`\begin{gathered}{ \large\sf\red{⟼ L=(110)/(7)}\end{gathered}`

⟼ L=15.5

Now

⟼ CF=L+r−DE

⟼ CF=15.7+10−16

⟼ CF=25.7−16

⟼CF=9.7cm