cos(116)

[Ninster]

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does anyone get why this becomes -cos(64)? I got this from the DAT Destroyer Jan 2008 - question 26.

They have drawn the graph and the angle ends up a bit in the S quadrant (top left - CAST) - so it should be sin64 no? How does it become -cos64?

Just a little confuzlled

 

[iwannabadentist]

cos(116) is in the 2nd quadrant (top left). cos is negative in the 2nd quadrant. 180-116 = 64. cos(64) is in the first quadrant (top right) so its positive. thus
cos(116) = -cos(64)

 

[nicz888]

you mean 180-116 = 64

 

[iwannabadentist]

you mean 180-116 = 64

^^ EDITED!

and yes thats what I meant.