This should be easy, but every time i type it in, i get the wrong answer! Please tell me what i am doing wrong!

Suppose is an angle in the second quadrant and

Then what is

and

.

And what is:

Answer in degrees and radians please!

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- Apr 25th 2007, 04:28 PM #1

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- Apr 25th 2007, 04:59 PM #2
so first thing you do is draw your triangle (if you want to use that method, you can also use trig identities to do it--i'll show you if you're interested)

so now, our right-triangle has an acute angle called u, with the opposite side, length 2, the hypotenuse, length 3, and the other side, length sqrt(5) (by pythagoras' theorem).

so cos(u) = adj/hyp = sqrt(5)/3 ...but wait, we are in the second quadrant, cosine is negative. so cosu = - sqrt(5)/3

the tangent is also negative in the second quad. so

tanu = - opp/adj = - 2/sqrt(5)

and we have:

u = arcsin(2/3) = 41.8103149 degrees = 0.729727656 radians

This is my 14 th post!!!!

- Apr 25th 2007, 05:03 PM #3

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