how to calculate a second radius

stefan_bruder

I need to sketch two radius one 200 mm and one 150 mm
first i create a variable radius (=200)
in the first raius i add "#radius" as dimension
in the second I try "#radius-50" , but this doesn't work, ( "#radius/2" works OK)?
what I am doing wrong

Alex_Kempen

Units. When adding or subtracting, the units on both sides of the equation must either both be defined or both be undefined. Thus, 2 in + 3 ft works, as does 2 + 3, but 2 in + 5 does not because the 2 has length units while the 5 is unitless. In your case, #radius - 50 mm will work properly. For more info, see "Using parameter expressions" here.