Observe the figure :

(a)

From the figure : and .

The angle is measured from the north.

Let the distance between and is .

Since the interior angle of the triangle at is , we have .

Now find the side .

Apply cosines law : .

Substiute , and .

Therefore, the distance from to is .

(b)

To find the bearing should the pilot use to fly directly from to ,we must know the angle .

Apply cosines law: .

Substiute and .

Divide each side by .

.

The bearing should the pilot use to fly directly from to is .

(a)

The distance from to is .

(b)

The bearing should the pilot use to fly directly from to is .