SIN function

[LROMERO3]

PLEASE HELP, Excel is driving me nuts
I am using the SIN function and excel is producing a different value than my calculator.

a quick example is SIN(90) which we all know equals 1
Excel formula is =SIN(90) which is producing 0.893997.....
I use the ROUND function to get the 1, but as i continue to use the SIN function on various other degrees, the totals are completely wack!
for example:
in calculator Sin(0.97)=0.0169
in Excel Sin(0.97)=0.824886
in calculator Sin(1.95)=0.034027
in Excel Sin(1.95)=0.92896

the 0.97 and 1.95 cells are set up to convert slopes (%) to degrees using the following function
cell 1 =3.4
cell 2 =ROUND(DEGREES(ATAN(R3/100)),2) giving me 1.95
which in turn is used in the
cell 3 =Sin(1.95)

What am i missing???
thank you in advance for your help!

 

[jproffer]

Because SIN (and COS, TAN, Etc) use Radians to calculate their results. You have to convert your 90° to radians before you can use these functions.

=SIN(RADIANS(90)) ...... ( =1)