There is no sin() function in microbasic
You can create one by loading an array of 90 variables, each containing the value of sine(index) * 1000, for example
SinTable[0] = 000
SinTable[1] = 017
SinTable[2] = 034
SinTable[3] = 052
SinTable[4] = 069
SinTable[5] = 087
...
SinTable[90] = 1000
Then, depending on which quadrant you are, you can use the table to compute the sine along the full 360 degrees
A sine function could be added to the language but there has been no demand for this before.