To find the area of the shaded triangle in the rectangle, let's analyze the given dimensions.

Step-by-Step Solution

1. Identify the Base and Height of the Triangle:

   • The triangle shares the bottom side of the rectangle as its base.
   • From the rectangle, we know that the base of the triangle is 8 units (the length of the rectangle).
   • The height of the triangle can be found using the total height of the rectangle (5 units) minus the height of the smaller top part of the triangle (3 units). So, the height of the triangle is: $5 - 3 = 2 \text{ units}$

2. Calculate the Area of the Triangle:

   • The area $A$ of a triangle is given by the formula: $A = \frac{1}{2} \times \text{base} \times \text{height}$
   • Substituting the values we found: $A = \frac{1}{2} \times 8 \times 2 = 8 \text{ square units}$

Therefore, the area of the shaded triangle is 8 square units. However, this answer does not match any of the options given (16, 20, 25, 32, 40). This discrepancy could be an error in the problem options or in the setup, but based on the given dimensions and our calculations, the correct answer should indeed be 8 square units.

Do you want more details or have any questions?

Here are five related questions to deepen your understanding:

1. How would the area calculation change if the height of the shaded triangle were different?
2. Can you find the area of the entire rectangle and compare it with the area of the triangle?
3. How would the solution differ if the triangle were an equilateral triangle?
4. How does the area formula for a triangle relate to that of other polygons?
5. Can you apply a similar method to find the area of trapezoidal shapes?

Tip: Always double-check dimensions in geometry problems, especially when certain values don't seem to match the provided answer options.