Do you want the area of the perimeter?
Either way you do not need to remember more formula!
Area of a circle is \(\pi r^2\)
If the angle at the of the sector is \(\theta ^\circ\)
(note this theta is in degrees)
then you will have \(\frac{\theta}{360}\;\; \text {of the circle}\)
So the area will be \(\frac{\theta}{360}\;\;\pi r^2\;\;\;units ^2\)
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Similarly the circumferenc of a circle is 2*pi*r
So the perimeter of the sector will be
\(Perimeter=\frac{\theta}{360}\;*2\pi r + \text {the two straight edges}\\ Perimeter=\frac{\theta \pi r}{180}\; + 2r\qquad units\)
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