To find the area of the triangle formed by points A(8, 2), B(6, 4), and C(8, 10) on a coordinate grid, we can use the formula for the area of a triangle given by its vertices:
\[ \text{Area} = \frac{1}{2} \left| x_1(y_2 - y_3) + x_2(y_3 - y_1) + x_3(y_1 - y_2) \right| \]
Where the points are:
- \( (x_1, y_1) = A(8, 2) \)
- \( (x_2, y_2) = B(6, 4) \)
- \( (x_3, y_3) = C(8, 10) \)
Substituting in the coordinates:
\[ \text{Area} = \frac{1}{2} \left| 8(4 - 10) + 6(10 - 2) + 8(2 - 4) \right| \]
Calculating each term:
- \( 8(4 - 10) = 8(-6) = -48 \)
- \( 6(10 - 2) = 6(8) = 48 \)
- \( 8(2 - 4) = 8(-2) = -16 \)
Now substitute these values back into the area formula:
\[ \text{Area} = \frac{1}{2} \left| -48 + 48 - 16 \right| \] \[ \text{Area} = \frac{1}{2} \left| -16 \right| = \frac{1}{2} \times 16 \] \[ \text{Area} = 8 \]
From the calculation above, we see that Luella multiplies \( \frac{1}{2} \) by \( 2 \) (which equals \( 1 \)) and then multiplies the result by \( 8 \).
Thus, the number Luella can use to complete the calculation is 8.