### Rangpur Higher Secondary 2011/6

Posted:

**Wed Feb 02, 2011 9:06 pm****Problem 6:**In the figure $AB = 12$ is the diameter of the circle. $MN||AB$ and $\angle BAN = 15^{\circ}$. Find the length of the arc $MN$.

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Posted: **Wed Feb 02, 2011 9:06 pm**

Posted: **Wed Feb 02, 2011 11:30 pm**

Let the centre is O.Connect O,N.ON=OA.Angle OAN=angleONA=15.AB is parallel to MN.Then angle ANM=15.SO that

angleONM=angleOMN=30.So angleMON=120.Then the length of the arc MN is (120/360).2.pi.6=4pi

angleONM=angleOMN=30.So angleMON=120.Then the length of the arc MN is (120/360).2.pi.6=4pi

Posted: **Thu Feb 03, 2011 12:28 am**

yes it's $4 \pi$

Posted: **Sat Aug 27, 2011 6:27 pm**

arc MN is (120/360).2.pi.6=4pi[/quote]

is it a generalized formula????/please explain it.

is it a generalized formula????/please explain it.

Posted: **Sat Aug 27, 2011 6:29 pm**

Mehfuj Zahir wrote:.Then the length of the arc MN is (120/360).2.pi.6=4pi

is it a generalized formula??please someone explain it.

Posted: **Sat Aug 27, 2011 7:13 pm**

yes the length of an arc= angle(radian)* radius(9-10 higher math book droshtobbo)