Biology A biologist wants to know the width w of a river in

Biology A biologist wants to know the width w of a river in order to properly set instruments for studying the pollutants in the water. From point A, the biologist walks upstream 100 feet and sights to point c. From this sighting, it is determined that theta = 58 degree (see figure). How wide is the river?

Solution

tan theta= opposite/adjacent

Here opposite is AB and adjacent =100 feet

therefore tan 58=AC/100

AC=100 tan58

AC= 160.03 feet

THerefore the width is 160.03 feet