Question 415687
add 360 to -540 and you get -180 degrees.


add 360 again and you get +180 degrees.


cos(-540) is equivalent to cos (180).


cos(180) = -1.


since cos = adj/hyp, and since hyp is always +, then adj must be equal to -1.


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take 405 degrees and subtract 360 from it to get 45 degrees.


tan (405) is equivalent to tan (45).


tan(45) is equal to 1


you have cos(-540) minus tan(405) = -1 - (-1) which should be equal to -2 if I did this correctly.


if I use my calculator, i get4 cos(-540) = -1 and tan(405) = 1


this makes cos(-540) minus tan(405) equal to -1 - 1 = -2.


not sure where you got .5 from.


I also converted to pi radians and got the same answer.


-540 degrees is equal to -9.424777961 radians


405 degrees is equal to 7.068583471 radians


cos(-9.424777961 radians) is equal to -1.


tan(7.068583461 radians) is equal to 1.


-1 minus 1 is equal to -2.


picture of your angles is shown below.


<img src = "http://theo.x10hosting.com/problems/415687.jpg" alt = "***** picture not found *****" / >


cos(-540) is equivalent to cos (-180) is equivalent to cos(180) = -1.


tan(405) is equivalent to tan(45) = 1.