sin390=sin30=1/2
cos390=cos30=√3/2
tan390=sin390/cos390=√3/3
sin(-7π/4)=sin(π/4)=√2/2
cos(-7π/4)=cos(π/4)=√2/2
sin(19π/3)=sin(π/3)=√3/2
cos(19π/3)=cos(π/3)=1/2
a= 390° －7π/4 19π/3
sina 1/2 √2/2 √3/2
cosa √3/2 √2/2 1/2
tana √3/3 1 √3
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