Answer
Find out the Area of a triangle .
To proof
Formula
Area of Triangle

Now vertices are D(3, 3) , E(3, −1) , and F(−2, −5) .

Solving the above


= -10 units²
(Neglected the negative sign as area cannot be negative.)
= 10 units ²
Area of a triangle is 10 units ²
Hence proved
Notice the first two vertices are reverse from each other (a,0) to (0,a)
the fourth vertex would be the reverse of the third one.
The fourth vertex would be (2a, a)
The answer is 96. just multiply 6 *2 =12*2=24*2=48*2=96