WebToolArcExact angle relationship
Radians measure angle by arc length relative to radius, so 180° equals π radians and 360° equals 2π. Common angles therefore have exact π-based forms even when the decimal radian display is rounded; keep the symbolic form when doing algebra or trigonometry by hand.
Exact conversion and numerical output
The exact relationship is 180 degrees = π radians, so degrees are multiplied by π/180 and radians are multiplied by 180/π. Familiar values such as 90°, 180°, and 360° therefore correspond exactly to π/2, π, and 2π even though their decimal approximations continue indefinitely.
Check the angle convention
Radians and degrees describe the same geometric angle, but software libraries often expect one unit explicitly. Before copying a decimal result into trigonometric code, verify whether the receiving function expects radians or degrees. For symbolic work, retaining a multiple of π can be more informative than rounding early; for numeric work, keep enough precision through intermediate steps and round only the final displayed result.