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### Rangpur Higher Secondary 2011/6

Posted: Wed Feb 02, 2011 9:06 pm
Problem 6:
2010_rang.png (23.15 KiB) Viewed 4872 times
In the figure $AB = 12$ is the diameter of the circle. $MN||AB$ and $\angle BAN = 15^{\circ}$. Find the length of the arc $MN$.

### Re: Rangpur Higher Secondary 2011/6

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

### Re: Rangpur Higher Secondary 2011/6

Posted: Thu Feb 03, 2011 12:28 am
yes it's $4 \pi$

### Re: Rangpur Higher Secondary 2011/6

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.

### Re: Rangpur Higher Secondary 2011/6

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.

### Re: Rangpur Higher Secondary 2011/6

Posted: Sat Aug 27, 2011 7:13 pm
yes the length of an arc= angle(radian)* radius(9-10 higher math book droshtobbo)