Polar parametric plots

These are pleasingly simple, and the plots can be generated with two or three lines of GNU Octave (Matlab if you prefer) code.

1. r=sin(6θ), θ=0..2π 
2. r=1+0.1 sin (50 θ/7), θ=0..14π 
3. r = 12 + 0.4 |θ-90|-0.01|θ-90|^2, θ = 30˚ .. 150˚