trigonometric equation formating

Can you post the failing worksheet or at least a screenshot!?
Have you tried what I show in the second line (pi/6) with the same error?

Have you tried too use the unit "deg" instead of "°" as seen in Terrys answer. You may explicitly type a multiplication after the number as Terry did, but it should not be necessary, just type "deg" after the number. That way you won't see a dot between the two

Are the letters "sin" upright or italic? When you click somewhere in "sin" and then look at menu Math-Style-Label, do you see "Function" as in the screenshot below or something else? If something else, does it help when you manually change the label to "Function"? Changing it to "Automatic" should work as well.

Actually I don't think that wrong labelling is the cause as the error message would be something else ("variable undefined") if that would be the case, but without seeing what you actually typed and without being able to play around with your worksheet we still are just stabbing in the dark 😞

You sure have typed the normal equal sign and not the fat boolean one which you get with Ctrl-+ !? Guess that could not be the cause, either, as if you use the boolean equal you won't get any error message - Prime would just wait for you to type in the RHS of the equation and tell it what you want to be done with the equation.

When you are using the inverse sinus (arcsin, in Prime called asin) and want to see the result in degree rather than the default radian, you unfortunately can't simply type "°" as we can do in real Mathcad. In Prime we get the exact error message you experience. You either have to type "deg" in the unit placeholder or uncomfortably chose the unit degree from the units menu.

But then you sure did not want the result of the sine function to be displayed in degree as the result isn't an angle anyway.

So again just a lot of shots in the dark...

Do you experience any problems with the attached worksheet?
It sure will look OK when you just open it as all you see is the last view I had over here. You should let the sheet recalculate (F9 or F5) to see what your installation of Prime thinks of it.

I am using Prime 6 but I don't think that such a severe bug could have found its way in P8 an remained undetected until now.

Here is what you should see, also after recalculation:

And one last try: You didn't do this (putting the angle outside of the parentheses), didn't you?

Hello,

I'm having the same problem, I read through the discussion here, make sure I'm using the correct operator, and started a whole new worksheet to make sure there are no interference, but still get a wrong calculation output involving trig: