Tolong dikerjaain ya?

1)b. dik:
AC=13
AB=5
dit:
sin a, cos a, tan a=?
peny
cos a=ab/ac= 5/13
bc^2=ac^2-ab^2
bc^2=13^2-5^2
bc^2=169-25
bc^2=144
bc=12
sin a=bc/ac= 12/13
tan a=bc/ab=12/5