Diagram for #18 (Hill Problem)

In case the image didn't work...
Draw a slanted line. This will be the hill. Next draw a vertical line going upward from a point on the hill. This will be your flag pole. Next draw a segmant that is perpendicular to your flagpole and intersects the hill. This is your horizontal. The angle between the horizontal and the hill is 17 in this problem. Draw a segmant connecting the top of the flagpole and the hill somewhere below the base. The length of this segment is the unknown. You now have a triangle and can use the law of cosines to determine the unknown.