Answer:
-1 or 5
Step-by-step explanation:
The area of a triangle is given by the formula ...
A = (1/2)bh
where b is the base length and h is the height.
Filling in the given information, we have ...
9 units² = (1/2)(6 units)h
(9 units²)/(3 units) = h = 3 units
The location of point c could be 3 units above y=2, at y=5, or it could be 3 units below y=2, at y=-1.
c could have a y-value of -1 or +5.
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The attached figure shows a couple of possibilities for the triangle.