Explanation:

- The formula to find the area of a trapezium (also known as a trapezoid) is: $(\frac{1}{2})\times (\text{sum of parallel sides})\times \text{height}$.

- You are given:

- The area of the trapezium: 1785 square feet.

- The height (distance between parallel sides): 35 feet.

- One of the parallel sides: 42 feet.

- Plug these into the formula:

$$

1785 = \frac{1}{2} \times (42 + \text{other side}) \times 35

$$

- Simplify to find the other parallel side:

$$

1785 = \frac{1}{2} \times 35 \times (42 + \text{other side})

$$

$$

1785 = 17.5 \times (42 + \text{other side})

$$

$$

102 = 42 + \text{other side}

$$

$$

\text{other side} = 60

$$

- Answer: Option 1 - 60 feet

.