Trigonometry Answers

A boat is headed at 115° and is traveling downstream at 28 mph. The stream is flowing S38°E at 11 mph. In what direction is the boat traveling? At what rate can it travel in still water?

Using radians, write the equation in the form AsinB(X+C)+D that oscillate s about the point y=8 if one cycle passes through the points (1.3, 8), (2.3, 8), (3.3, 8) and the wave has a maximum at( 2.8, 11)

using radians, write the equation in the form AsinB(X+C)+D that oscillate about the point y=8 if one cycle passes through the points (1.3, 8), (2.3, 8), (3.3, 8) and the wave has a maximum at (2.8, 11)

Use the double angled formula to prove the following expressions. (i) Given that cos(x+30)=3cos(x-30), prove that tanx= - root 3/ 2 (ii)prove that 1-cos2x/sin2x = tan x (iii) verify that x= 180 is a solution of the equation 2x=2-2cos2x (iv) Using the resulat from part (ii) or otherwise find the two other solutions

Had this previously answered to which I can solve parts 1 & 2 and expand upon them but I am a little confused with parts 3 and 4 ...

Can any one elaborate?

Thanks

An observation tower 70m high is on verbal cliff overlooking a boy. From the top of the tower, a ship is sighted with an angle of depression 15°40' measured from the base of the tower. Compute the distance of the ship from the cliff & find the height of the cliff.