# math

posted by .

For which angles beta, with 0 degrees less than/equal to beta less than/equal to 180 degrees,
is sin 3beta equal to -1?

a) 30 degress and 150 degrees
b) 60 and 120 degrees
c) 90 degrees
d) 0 and 120 degrees

I think it is C because sin of (3 x 90 = 270) 270 degrees is -1?

Did I do this right? Or did I do something that cannot be done?
Thank you.

• math -

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