Fiona draws a triangle on a coordinate grid with vertices at C (6,2), B (4,6), and A (1,2). What is the area in square units of Fiona's triangle?

The area of the triangle is _ square units.

1 answer

To find the area of the triangle with vertices at points \( C(6,2) \), \( B(4,6) \), and \( A(1,2) \), we can use the formula for the area of a triangle given by the coordinates of its vertices:

\[ \text{Area} = \frac{1}{2} \left| x_1(y_2 - y_3) + x_2(y_3 - y_1) + x_3(y_1 - y_2) \right| \]

Let the coordinates of the vertices be:

  • \( A(1, 2) \) has \( x_1 = 1 \), \( y_1 = 2 \)
  • \( B(4, 6) \) has \( x_2 = 4 \), \( y_2 = 6 \)
  • \( C(6, 2) \) has \( x_3 = 6 \), \( y_3 = 2 \)

Now, substituting these coordinates into the formula:

\[ \text{Area} = \frac{1}{2} \left| 1(6 - 2) + 4(2 - 2) + 6(2 - 6) \right| \]

Calculating each term:

  1. \( 1(6 - 2) = 1 \cdot 4 = 4 \)
  2. \( 4(2 - 2) = 4 \cdot 0 = 0 \)
  3. \( 6(2 - 6) = 6 \cdot -4 = -24 \)

Now putting it all together:

\[ \text{Area} = \frac{1}{2} \left| 4 + 0 - 24 \right| = \frac{1}{2} \left| 4 - 24 \right| = \frac{1}{2} \left| -20 \right| = \frac{1}{2} \cdot 20 = 10 \]

Thus, the area of Fiona's triangle is

\[ \boxed{10} \quad \text{square units.} \]