Question 1: Please help, look at the picture below.

1.98

Step-by-step explanation:

The triangle in the figure is a right triangle, which has a 90 degrees angle.

The side opposite to the right angle is called hypothenuse, and it is the longest side of the triangle.

For a right triangle, the following relationship exists between angles and sides:

(1)

where is any of the other 2 angles in the triangle, and opposite means "side opposite to the angle" and adjacent means "side adjacent to the angle".

In this problem, we know that the angle at D is

We also know that the hypothenuse is

Therefore, in order to measure EF, we can use eq.(1). We find: