Math

Cos180* - Sin90* + Cot45* - Csc30* - Sec240* - Tan315*

How do I do this?

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  1. all these are standard angles for which you should know the trig ratios

    cos 180 = -1 , look at the cosine curve
    sin 90 = 1 , look at the sine curve
    cot 45 = 1/tan45 = 1/1 = 1 , look at your 45-45-90 triangle
    csc 30 = 1/sin30 = 1/(1/2) = 2 , look at the 30-60-90 triangle
    sec 240 = 1/cos240 = - 1/cos60
    = -1/(1/2) = -2 , using the CAST rule and 30-60-90 triangle
    tan 135 = -tan45 = -1

    now just add them up

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    posted by Reiny
  2. these are all standard angles you should know by heart. It will save you a lot of trouble working them out all the time.

    -1 - 1 + 1 - 2 + 2 + 1 = 0

    It also involves knowing the signs of the trig functions in the various quadrants, and how to figure the reference angle.

    Also, lose the capitalization.

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    posted by Steve

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