inverse trig HELP PLEASE!!
posted by Adrianna .
Write the general solution to y = arcsin (0.6428).
40°±360°k
140°±360°k
220°±360°k
320°±360°k
How do I find the right answer? I am like seriously stuck. I need help please.

set your calculator to degrees (the DRG key)
enter:
2ndF
sin
.6428
=
you should get 40.00...
since sinØ has a period of 360° , adding or subtracting multiples of 360° will produce the same answer
so 40° ± 360k would be the general solution
you might check with some arbitrary value of k
say k = 5
then 40 + 5(360) = 1840
sin 1840° = .64278 , close enough!
(on some calculators you have to enter the argument first,
e.g.
.6428
2ndF
sin
you will have to test your device.