Mistakes give rise to Problems- 11

In maths we see the following property for multiplication of numbers,$\color{#20A900}{a(b\times c) = b\times a(c)}$

But if you do that here, $\sin (3\times a) = 3\times \sin (a)$ then it will be a $\color{#D61F06}{\textbf{Big Mistake !!!}}$

But for how many angles $\color{#3D99F6}{a}$ such that $-100\leq a \leq 100$, is the above said "false" property seen to be "true" ?

Details and assumptions:-

Angle measuring $\color{#3D99F6}{a}$ is actually measuring " $\color{#3D99F6}{a}$ radians"

This problem is a part of my set Mistakes Give Rise to Problems