Strategy used to approach a weird quadrilateral when you are not sure about the Lengths of the Sides:
Fill in the Extra "Parts" to make it a Rectangle or Square with 90 Degree Perpendicular Angles
Area of Quadrilateral in question =
(Area of your Created Rectangle) - (Parts, which usually consist of Right Triangles, that are NOT part of the Quadrilateral in question)
In addition to the Points Given, Fill in the following Points in order to Create our Rectangle:
Point (15 , 6) --------> and connect a Straight Horizontal Line from (2 , 6) to (15 , 6) that has Length of 13 Units
and
Point (2 , -4) -------> and connect a Straight Horizontal Line from (15 , -4) to (2 , -4) that has Length of 13 Units
if done correctly, you know have 2 Right Triangles that you added to the Given Quadrilateral in the Question and this Comes together to form a RECTANGLE
I. Area of Created Rectangle
13 Units = Length (as shown above)
Width = (Y-Coordinate of Point (15 , 6) ) - (Y-Coordinate of Point (15 , -4) = 10 Units
Area of Created Rectangle = 13 * 10 = 130 Units
II. Area of 2 Right Triangles
(1st) The Right Triangle on the Bottom of the Created Rectangle with Points:
(2 , -2) ----- (2 , -4) ------ (15 , -4)
will have Leg = 13 and Leg = 2
Area = (1/2) * 2 * 13 = 13 Units
(2nd) the Right Triangle on the Top of the Created Rectangle with Points:
(2 , 6) ------ (15 , 6) ------ (15 , 2)
will have Leg = 13 and Leg = 4
Area = (1/2) * 4 * 13 = 26
Finally, the Area of the Quadrilateral in question is equal to:
(130) - (13) - (26) = 91
-A- is the correct Answer