What is the area of the triangle with vertices at (1, 3), (7, 3), and (4, 8)?

✓ Correct Answer: Option C

The base of the triangle can be formed by the points (1, 3) and (7, 3), which lie on a horizontal line. The length of this base is |7 - 1| = 6 units. The height is the perpendicular distance from the third vertex (4, 8) to the line y=3, which is |8 - 3| = 5 units. Area = (1/2) * base * height = (1/2) * 6 * 5 = 15 square units.