How to Use
Direct mode
Type the known quantity with its parameter name:
circle(r=5) → radius = 5
circle(d=10) → diameter = 10
circle(c=31.416) → circumference
circle(a=78.54) → area
Interactive mode
Type circle and press ENTER. The calculator will ask which quantity is known (r, d, c, or a), then prompt for its value.
Example
circle(r=5) returns:
Diameter = 10
Circumference = 31.415927
Area = 78.539816
Precision
Press FIX 2 (FIX key then 2) to round results to 2 decimal places. Press SHIFT FIX (CLRFIX) to restore full precision.
Formulas
Circumference
C = 2 × π × r = π × d
Area
A = π × r²
Radius from circumference
r = C / (2 × π)
Radius from area
r = √(A / π)