Calculate the area of a regular octagon inscribed in a unit circle.

In quadrilateral ABCD, AB=3, BC=4, CD=5, and DA=6. The length of diagonal BD is 7. Calculate the length of the other diagonal.

From the top of an observation post that is 90 meters high, a ranger sights a campsite at an angle of depression of 10°. Turning in a different direction, the ranger sees another campsite at an angle of depression of 13°. The angle between these two sight lines is 35°. How far apart are the campsites?