Single correct option
What is the area of the triangle with vertices (1, 2), (4, 6) and (7, −1)?
- A. 15
- B. 16.5
- C. 18
- D. 33
Show answer and solution
Answer: (B) 16.5
Area = ½ |x₁(y₂ − y₃) + x₂(y₃ − y₁) + x₃(y₁ − y₂)|
= ½ |1(6 + 1) + 4(−1 − 2) + 7(2 − 6)|
= ½ |7 − 12 − 28| = ½ × 33 = 16.5.
The trap option 33 is what you get if you forget the ½.
Tip: the shoelace formula works for any polygon given its vertices in order.
= ½ |1(6 + 1) + 4(−1 − 2) + 7(2 − 6)|
= ½ |7 − 12 − 28| = ½ × 33 = 16.5.
The trap option 33 is what you get if you forget the ½.
Tip: the shoelace formula works for any polygon given its vertices in order.
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