What is the area of a triangle with vertices at open paren negative 2 comma negative 1 close paren , open paren 4 comma negative 1 close paren , open paren 6 comma 5 close paren ?

The first two vertices, (−2, −1) and (4, −1), form a horizontal base of length 4 − (−2) = 6 units. The third vertex is 6 units above that base, since its y-coordinate is 5 and the base has y-coordinate −1. The area is (1/2)(6)(6) = 18 square units, so the answer is D, 18 square units.

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