Trig Functions on the Cartesian Plane  TOPIC_SOLVED

Trigonometric ratios and functions, the unit circle, inverse trig functions, identities, trig graphs, etc.

Trig Functions on the Cartesian Plane

Postby jwroblewski44 on Sat Sep 14, 2013 12:59 am

Hello all.

I am working on finding the trig rations of angles that go through a set of x-and-y coordinates ( x , y ). I was doing pretty well; doing the problems, then confirming my answer with the back of the book answers. Then I got to the point ( -10/3 , 4/3 ). X and Y are obvious as they are given as coordinates. But this is where I differ from the text. My answer for the distance, or r, is 2*sqrt(29)/3. And with that number, the sin of angle theta was 2*sqrt(29)/29. The book gave the same answer, but it was negative. I don't see where this negative came from. Can anyone point out my mistake for me?
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Re: Trig Functions on the Cartesian Plane

Postby little_dragon on Sat Sep 14, 2013 1:10 am

jwroblewski44 wrote:Hello all.

I am working on finding the trig rations of angles that go through a set of x-and-y coordinates ( x , y ). I was doing pretty well; doing the problems, then confirming my answer with the back of the book answers. Then I got to the point ( -10/3 , 4/3 ). X and Y are obvious as they are given as coordinates. But this is where I differ from the text. My answer for the distance, or r, is 2*sqrt(29)/3. And with that number, the sin of angle theta was 2*sqrt(29)/29. The book gave the same answer, but it was negative. I don't see where this negative came from. Can anyone point out my mistake for me?

the point is in Q2 so sine is y/r & sine is positive
i think the book has a typo
try asking your teacher
:wave:
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Re: Trig Functions on the Cartesian Plane  TOPIC_SOLVED

Postby jwroblewski44 on Sun Sep 15, 2013 11:39 pm

Thank you!
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