You can use GeoGebra to transform a trigonometric expression into a harmonic oscillation.
GeoGebra Instruction 1
CAS under View in Menu. CAS, type TrigCombine(<Expression>, <Target Function>)
where
<Expression> is the expression for the trigonometric function that you want to transform, and
<Target Function> is sin(x).
Click Solve if you want an exact representation, or
Solve Numerically if you want a numeric one.
Example 1
Transform
into a harmonic oscillation.
Type
TrigCombine(sin(2x)-4*cos(2x),sin(x))
and click Solve Numerically , giving the answer