# sector area

• Mar 11th 2010, 02:08 PM
Wilmer
sector area
Chord length c in circle radius r.
What is area of the sector created, in terms of c and r?
• Mar 11th 2010, 02:33 PM
Quote:

Originally Posted by Wilmer
Chord length c in circle radius r.
What is area of the sector created, in terms of c and r?

Hi Wilmer,

You can use the Cosine Rule.

The sector angle C is derived from $c^2=R^2+R^2-2RRCosC$

$C=Cos^{-1}\left(\frac{2R^2-c^2}{2R^2}\right)$

Then use this C for the sector area.
(Coffee)
• Mar 11th 2010, 02:51 PM
Plato
• Mar 11th 2010, 04:16 PM
Wilmer
Thanks (I knew that), BUT without using trig.
In terms of r and c ONLY.