The Pen Is Driven by the Angle

You'll learnto plot a polar curve one point at a time before sweeping it.

A polar graph is not plotted point by point, it is swept. The angle turns counterclockwise while r says how far from the pole the pen should ride. Watch the wave on the right issue the instructions and the curve on the left carry them out, and watch what happens when r is told to go negative.

9 STEPS · 6 QUICK CHECKS · CIRCLES · ROSES · LIMAÇONS · NEGATIVE r · v2

the wave is the instruction sheet

Before you start

What you're looking at

The simple equation r = 2, with a single point built by choosing θ, computing r, and plotting it.

The question

For this angle, how far from the pole does the pen ride?

Watch for

One point made first, the r-versus-θ graph held back, and the pen reversing when r goes negative.

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