Since area = pi * r^2 we can rephrase this question as: What is the radius OM = OR = OS = ON?

1) MN is perpendicular to RS.
- This tells us MOT is a right triangle but without more info isn't going to help us find the radius
-----> INSUFFICIENT



2) The area of triangular region OMT is 4.
- Doesn't help cuz we don't know if MO is a height or OT is a base
------> INSUFFICIENT

1 & 2) Now we know MOT is a right triangle with area 4.
- area triangle = .5 * b * h
- area MOT = 4 = .5 * MO * OT
- This is about as far as we can get. We can't solve for MO.
- We can also use examples to show that we can get an area of 4 with multiple values for MO

Example 1:
MO = 8
OT = 1
area MOT = .5 * 8* 1 = 4

Example 2:
MO = 4
OT = 2
area MOT = .5 * 4 * 2 = 4

Multiple radii = multiple areas for circle ----> INSUFFICIENT

Answer: E

Can you show how you got a different answer?