Question 1061199
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The area of a sector of a circle is given by 1/2r^2 theta(theta in radians)so that an area element triangle A=1/2r^2 Triangle theta. 
Use this to calculate the area of a semi-circle.
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The area of a semi-circle is {{{(1/2)*pi*r^2}}}.     (*)


Independently of any hints.


Or, if you want to use that hint, use {{{theta}}} = {{{pi}}} in your formula to get the area of a semi-circle.
Surely, you will get the same as (*).
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