Question

if 3sinA=1,find sin3A

Answer 1

I don't know how to solve only with the variable A, but if you're allowed to use calculator you see that
\[\Large{3\times sin(A)=1~then:~sin(A)=\frac{1}{3}}\]
you can find the arcsine of 1/3 and subtitute it by A and find sin(3A)
\[\large{arcsine(\frac{1}{3})=19.47~approx.~then:~sin(3\times19.47)=sin(58.41)}\]

Answer 2

almost sin(60) wich would be \[\large{\frac{\sqrt{3}}{2}}\]