Trigonometry - Trigonometric Graphs and Parameters

Trigonometry - Trigonometric Graphs and Parameters

Changing the sign of \(a\) reflects the graph in its midline. The period is unchanged; assume \(b>0\).

\(\text{Sine/cosine amplitude}=|a|\qquad\text{Extremes}=c\pm|a|\)

CurveReflection lineAmplitudeWhat changes
\(y=a\sin(bx),\ a<0\)
\(y=a\sin(bx)+c,\ a<0\)
\(y=a\cos(bx),\ a<0\)
\(y=a\cos(bx)+c,\ a<0\)
\(y=a\tan(bx),\ a<0\)

For \(y=2-3\cos2x\), the midline is \(y=2\) and the amplitude is \(3\).

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