Find all the angles between 0º and 360º for which sin 0 =–0.707.
a.
45° and 135°
b.
135° and 225°
c.
45° and 315°
d.
225° and 315°

Question

anonymous · Answer

that dosnt really help me much

psymon · Answer

Alright, I wasnt sure if you'd seen values like that or not.

anonymous · Answer

you can skip A and C because $\sin(45)>0$

anonymous · Answer

Take the inverse sin of -0.707 on your calculator and you should get -45 degrees. That is in the 4th quadrant and is the same thing as 360 - 45 or 315. So we now know the answer is c or d
The other answer has to be in the 3rd quadrant. 225 is in the 3rd, 45 is in the first. So the answer is D

anonymous · Answer

sine in negative in quadrants 3 and 4

psymon · Answer

But yeah, without just using a calculator or being given the answer, you just have to know where sin would actually be negative, which as satellite said, is in the 3rd and 4th quadrants. Then it's just realizing which angles are actually in those quadrants.