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'Tangled Trig Graphs' printed from http://nrich.maths.org/
This anonymous solver correctly identified
the remaining curves, and explained how to draw a graph of sin $x$
using the cosine function:
The red graph has equation $y=-\sin x$.
The light blue graph has equation $y=\sin 2x$.
The grey graph has equation $y=\sin 3x$.
The dark blue graph has equation $y=-\sin 3x$.
The graph $y=\cos x$ is the same shape as $y=\sin x$ but shifted
along. I can make the shape of $y=\sin x$ by drawing the graph