Pick a locus or an HSC-style region. Drag the coloured handles to change it, then move P to test whether a point belongs.
Snap is on: points move in steps of 0.5. Tap the plane to move P, drag empty space to pan, scroll or use ± to zoom. Arrow keys move P when the plane is focused.
arg z is the principal argument, −π < arg z ≤ π, and is undefined at z = 0. Solid boundaries are included, dashed boundaries are not; filled dots are included, open dots are excluded. Syllabus: Complex numbers, “Describing lines, curves and regions” (Mathematics Extension 2, 2024).
McIntyre Maths