i must be putting this into my calc wrong i keep getting .86217 as a result for tan-1(14/12) any help im useing a ti-89

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Matt---Alei001 is correct.  When you have arctan(x) or inverse tan (x) you should always say to yourself...what angle (theta) will result in a tan (theta) = 14/12.  You should know that 45 degrees has a tan of 1 so it should be slightly larger than 45-----> 49.4 degrees.  This is the same for arcsin and arccos, etc.