For Area of shaded region, we need to subtract the area of sector from the area of circle..

For area of sector, we need the angle subtended AND the radius.

2 tells us angle is 60
1 gives us the radius.
C

Area of the shaded region?

= (Angle MON)/360 * (pi)* r^2

So you need Angle O and value of r?

Statement 1
circumference = 2*pi*r
2*pi*r = 30

you can find the value of r
but you dont know value of Angle O

Insufficient

Statement 2
MN = NO = OM

Angle O = 60 degrees
but we have no idea about value of r

Insufficient


But combining the two..
we know value of r and angle MON
and thus we can find the Area of the shaded region.


OptionC

Area of shaded region = Area of circle - Area of Sector

1)Gives area of circle but nothing about sector.Not sufficient.
2)Each angle of triangle =60.
Thus area of sector = 60/360 * Area of circle.
Not sufficient.

Combining you can solve the question.Do not calculate the actual answer.OA is C

IMO C

angle MON/360 * pi * r ^2 = ?

1.Gives r, no info on angle MON.
2.Give angle MON, no info on radius

Combining both we can get the answer.