Question

8.8 km
7.8 km
what is the perimeter? if necessary, round to the nearest tenth.
_____ kilometers

Explanation:

Step1: Find side $a$ via Pythagoras

$$a = \sqrt{8.8^2 - 7.8^2}$$
$$a = \sqrt{77.44 - 60.84} = \sqrt{16.6} \approx 4.1$$

Step2: Sum all sides for perimeter

$$\text{Perimeter} = 7.8 + 4.1 + 8.8$$

Answer:

20.7 kilometers