Question: What is the area of a triangle with vertices at (1, 1), (4, 5), and (7, 2)?

Options:

1. 10
2. 12
3. 14
4. 16

Correct Answer: 12

Solution:

Area = 0.5 * |x1(y2 - y3) + x2(y3 - y1) + x3(y1 - y2)| = 0.5 * |1(5 - 2) + 4(2 - 1) + 7(1 - 5)| = 0.5 * |3 + 4 - 28| = 0.5 * 21 = 10.5.