Answer:
10 units²
Explanation:
The length of side AB is 3 -(-1) = 4 units long. This is the base of the triangle.
The distance from vertex C to the line x=3 is 3-(-2) = 5 units. This is the altitude of the triangle.
The area is half the product of altutude and base length.
... A = (1/2)bh = (1/2)(4)(5) = 10 . . . units²