[Maxima] how to use degree in sin function

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(%i9) sin(%pi/6);
(%o9) 1/2
(%i10) sin(30);
(%o10) sin(30)

we have 30 degree =%pi/6 radian
the sin function is use radian.
how can I use degree in sin funciton
for example 
I want input sin(30) =1/2
I wish the students can free input degree and they can get the sin function answer.





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