To find the total length of the race course around the triangle-shaped grassy area, we need to add the lengths of each side of the triangle.
Given the lengths:
- Side 1: 1.524 km
- Side 2: 2.4 km
- Side 3: 1.83 km
Now, we'll add these values together:
\[ 1.524 , \text{km} + 2.4 , \text{km} + 1.83 , \text{km} = 5.754 , \text{km} \]
Therefore, the total length of the race course is B. 5.754 km.