Maths Help - Trigonometry?

Science & Mathematics by Anonymous 2018-07-12 07:34:28

Social Science

4 answers

Two points, A and B, are directly opposite on the two banks of a river. A surveyor walks down one bank from A to a point C, a distance of 80m. He finds the angle ACB to be 39 degrees. How wide is the river between points A and B?

Anonymous

Width of river: tan(39)*80 = 64.78m to two decimal places
Anonymous

Let x be the river width. tan39 = x/80 x = 64.782 m
Anonymous

According to the figure: tan(39) = AB/AC AB = AC.tan(39) → given that: AC = 80 m AB = 80 * tan(39) AB ≈ 64.782722 m AB = 64.79 m
Anonymous

tan 39 ⁰ = x / 80 x = 80 tan 39 m x = 64•8 m _______ required width.