3D Trigonometry Help (1 Viewer)

[calebwhitaker199]

 

[FrankXie]

draw a 2D diagram like this: ABCD is a rectangle where AB=8, BC=15 and BC is first on the ground level, now rotate the rectangle around point C so that point A is 12 above the ground.

solve the 2D problem and we can manage to establish the equation

and the exact solution is

 

[Ambility]

Here's my solution. Basically I calculated the angle the bigger angle marked and subtracted the angle from it to get angle .

http://i.imgur.com/uQNUs4e.jpg

EDIT: Aaannnnddd.... I just realised I incorrectly rounded my last answer. Please ignore that mistake, the method is still correct.

 

[braintic]

draw a 2D diagram like this: ABCD is a rectangle where AB=8, BC=15 and BC is first on the ground level, now rotate the rectangle around point C so that point A is 12 above the ground.

solve the 2D problem and we can manage to establish the equation

and the exact solution is

By dropping a perpendicular to the floor from the point where the cylinder touches the ceiling, that exact value appears straight off the diagram without going through that equation.

Edit - oops, that is Ambility's solution.

 

[calebwhitaker199]

Thanks heaps !