we are going to use the property that sin(-x) = -sinx
and csc x = 1/sinx
csc(-390)
= 1/sin(-390)
= 1/-sin390
= 1/-sin30 , 390 is coterminal with 30
we know sin 30 = 1/2
so
cosc(-390)
= 1/(-1/2)
= -2
How do you figure out the csc(-390deg)?
Thank you very much!
1 answer