4. Find the area of the shaded region in Fig, where a circular arc of radius 6 cm has been drawn with vertex O of an equilateral triangle OAB of side 12 cm as centre.
Area of the shaded region is given by = Area of triangle + Area of the circle - Area of the sector
Area of the sector is : -
or
And, the area of the triangle is :
And, the area of the circle is :
or
or
Hence the area of the shaded region is:-
or