Explanation
Correct answer: 49/2,24.5,24.50.
5\left( - 3 , 4 \right)\left( 5 , 3 \right)\left( 4 , - 3 \right)\left( - 3 , 4 \right)\left( 5 , 4 \right)\left( 5 , - 3 \right)\left( - 3 , - 3 \right)\left( 5 , 4 \right)\left( 5 , - 3 \right), or $7\left( 5 , 4 \right)\left( - 3 , 4 \right), or $8\left( 7 \right) \left( 8 \right). One of the triangles that lies inside the rectangle but outside triangle A is formed by the points , , and . The length, in units, of a base of this triangle can be found by calculating the distance between the points and . This distance is $4 - 3. The corresponding height, in units, of this triangle can be found by calculating the distance between the points and . This distance is $5 - \left( - 3 \right). It follows that the area, in square units, of this triangle is , or $4\left( 4 , - 3 \right)\left( 5 , 3 \right)\left( 5 , - 3 \right)\left( 5 , 3 \right)\left( 5 , - 3 \right), or $6\left( 5 , - 3 \right)\left( 4 , - 3 \right), or $1\frac{1}{2} \left( 1 \right) \left( 6 \right). The third triangle that lies inside the rectangle but outside triangle A is formed by the points , , and . The length, in units, of a base of this triangle can be found by calculating the distance between the points and . This distance is $4 - \left( - 3 \right). The corresponding height, in units, of this triangle can be found by calculating the distance between the points and . This distance is $4 - \left( - 3 \right). It follows that the area, in square units, of this triangle is , or $24.5, or $24.5$. Note that 49/2, 24.5, and 24.50 are examples of ways to enter a correct answer.
Desmos solution:
Note: Use the shoelace formula with the three plotted coordinates, then take half the absolute value.
Enter in Desmos:
Reviewed and rewritten by CookSAT