You are hiking along the edge of the Green River which is ru

You are hiking along the edge of the Green River (which is running straight in the area of interest). Straight across from you on the opposite shore there is a particularly noticeable boulder at the edge of the river. You walk 120 feet along the shore of the river, and now the line from you to the boulder makes an angle of 35 degree with the edge of the river. You whip out your trusty scientific calculator and deduce that the width of the river at this point is feet.

Solution

Draw a picture. ”Straight across” means that the line from you to the boulder forms a right angle with the shore of the river.

Here in right angle triangle,

Base = B = 120 feet

width of the river = Perpendicular = P = ?

Then, P/B = tan35

  width of the river = P = 120*tan35 = 84.0249 feet