Final answer:
The area of the kite with diagonals of 5.1 ft and 8 ft is calculated using the formula for the area of a kite and is found to be 20.4 ft².
Step-by-step explanation:
The area of a kite can be found by using the formula Area = (d1 x d2) / 2, where d1 and d2 are the lengths of the diagonals of the kite. In this case, the diagonals are 5.1 ft and 8 ft. So, the area of the kite is calculated as follows:
Area = (5.1 ft x 8 ft) / 2
Area = (40.8 ft²) / 2
Area = 20.4 ft²
Therefore, the correct answer is a. 20.4ft².