Hello student,
As you have not clearly mentioned the picture in your question itself and because of limitation of the number of answering boths available on this platform it's very difficult to mathematically and diagrammatically help you with the solution regarding your question.
I would encourage you that if you have any other doubt regarding any specific topic feel free to post it here...
Question : If $4 \sin ^2 \mathrm{A}-3=0$ and $0 \leq \mathrm{A} \leq 90^{\circ}$, then $3 \sin \mathrm{A}-4 \sin ^3 \mathrm{A}$ is:
Option 1: $\frac{1}{2}$
Option 2: $\sqrt{\frac{3}{2}}$
Option 3: $0$
Option 4: $1$
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