BTGmoderatorDC wrote:

What are the coordinates of point B in the figure above ?

(1) The area of ∆ABC = 30

(2) Length of CB = 13

OA D

Source: Magoosh

IMPORTANT: For geometry Data Sufficiency questions, we are typically checking to see whether the statements "lock" a particular angle, length, or shape into having just one possible measurement. This concept is discussed in much greater detail in the video below.

Target question: What are the coordinates of point B ?

NOTE: points A and C are LOCKED in their positions. Since ∠CAB = 90º, we know that point B is SOMEWHERE along the line y = 4. So, some of the MANY possible cases are as follows:







Notice that, for EACH different position of point B, ∆ABC has a different area and side CB has a different length.

Okay, onto the statements...
Statement 1: The area of ∆ABC = 30
As I mentioned above, for EACH different position of point B, ∆ABC has a different area.
So, knowing that the area is 30, LOCKS point B into ONE AND ONLY ONE location.
In other words, statement 1 LOCKS IN the shape/dimensions of ∆ABC, which means there must be only one location for point B.
As such, statement 1 is SUFFICIENT

Statement 2: Length of CB = 13
As I mentioned above, for EACH different position of point B, side CB has a different length.
So, knowing that side CB has length 13 LOCKS point B into ONE AND ONLY ONE location.
In other words, statement 2 LOCKS IN the shape/dimensions of ∆ABC, which means there must be only one location for point B.
As such, statement 2 is SUFFICIENT

Answer: D

RELATED VIDEO
https://www.youtube.com/watch?v=wetqSGMdY7Y