If a triangle has a base of 8 and a height of 5, what is its area?

To calculate the area of a triangle, you use the formula:

[ \text{Area} = \frac{1}{2} \times \text{base} \times \text{height}

]

In this scenario, the base of the triangle is given as 8 and the height is 5. Plugging these values into the formula gives:

[ \text{Area} = \frac{1}{2} \times 8 \times 5 ]

First, multiply the base and the height:

[ 8 \times 5 = 40 ]

Then, take half of that product:

[ \frac{40}{2} = 20 ]

Thus, the area of the triangle is 20 square units. This matches with the selected answer, confirming that it is indeed the correct choice. The steps illustrate how the dimensions of the triangle directly apply to the area formula, leading to a straightforward calculation of the triangle's area.