the distance across a river is to be determined by two sightings, a and b, from one side of the river. a reference point is chosen on the opposite side of the river. from sighting point a the reference point is determined to be 600 from a line parallel to the river. sighting point b is chosen to be directly opposite the reference point so that the sighting angle is 900 from the line parallel to the river. the distance between a and b is measured to be 20 meters. find the distance across the river.
hint: sketch a right triangle diagram for the situation. you might need:
cos 60degrees = 1/2 , sin 60degrees = sqrt3/2