without calculator solving e.g. cos (1/2)

[monkeywantsabanana]

You can use the Hand Trick!

Our teacher showed us this, the rapping starts at 1:00 - http://www.youtube.com/watch?v=mg8IDXpmc-U

(:

[onur369]

To be honest I do it in a wierd way. pi/6 = 180/6=30 , pi/4=180/4=45, pi/2=90 pi is 180...
For the balues like sin pi/6= 1/2 I think of it this way.  Increase the numerator by one and square root it. sin(pi/6) = sq(1)/2 =1/2 and then sin(pi/4) = sq(2)/2 than sin(pi/3)= sq(3)/2
For cos I decrease the value of numerator by one, cos(pi/6) = sq(3)/2  cos(pi/4)= Sq(2)/2 and cos(pi/2) = Sq(1)/2=1/2, as squareroot of 1 is 1.

Its weird but it works.

[b^3]

The way I do it is to think the small angle means cos is big and sin is small, and the large angle means cos is small and sin is big.
i.e. small=1/2
big =root(3)/2
e.g. sin(pi/6) is smalll angle, so sin is small so 1/2
e.g. cos(5pi/6)=-cos(pi/6) so small angle, so cos is big so root(3)/2
Just remember to apply CAST for the correct signs.

My method is a bit confusing but it works for me, I like to visualise it in my head when I do it.

[taiga]

I can't remember them, I just draw the triangles each and every time. Never fails me.

[tony3272]

Yeah i just imagine the triangles in my head every time i need to work it out.

[Hutchoo]

You can use the Hand Trick!

Our teacher showed us this, the rapping starts at 1:00 - http://www.youtube.com/watch?v=mg8IDXpmc-U

(:

lol. Remembering that rap is probably harder than remembering the ratios/exact values

[Anon123]

remember the triangles, they are VERY, VERY useful

[tha boss]

thanks for all your help  ill try memorizing it