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# Trig problem watch

1. This question has been annoying me for a while. I don't understand what I'm doing wrong. The answer is an integer between 0 and 999. The question is attached

Firstly I did the Cos^-1 of 1/3 and then multiplied it by 2 to calculate angle c. Then I did 180 - angle C to get:

38.94244127. Then I subtracted Pi and divided it by 2 to get 17.90042431.

Then I put this into tan^2 and I got 0.1043285979, which is obviously not an integer.

I can't figure out where I went wrong or if I'm missing something obvious.

On a side note, how do you make latex bigger?, I forgot.
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2. You should be working in radians. The answer is a small integer.
3. (Original post by ThatPerson)
This question has been annoying me for a while. I don't understand what I'm doing wrong. The answer is an integer between 0 and 999. The question is attached

Firstly I did the Cos^-1 of 1/3 and then multiplied it by 2 to calculate angle c. Then I did 180 - angle C to get:

38.94244127. Then I subtracted Pi and divided it by 2 to get 17.90042431.

Then I put this into tan^2 and I got 0.1043285979, which is obviously not an integer.

I can't figure out where I went wrong or if I'm missing something obvious.

On a side note, how do you make latex bigger?, I forgot.
Why?
4. (Original post by electriic_ink)
Why?
It is a Triangle ABC. Triangles have total angles of 180 degrees, so once I calculated angleC, I subtracted it from 180 to get the sum of angleA plus angle B, which was needed for the next question.
5. (Original post by Mr M)
You should be working in radians. The answer is a small integer.

How do I know if I'm meant to be using radians?
6. (Original post by ThatPerson)

How do I know if I'm meant to be using radians?
Yes.

Isn't the pi and the absence of the degree symbol a bit of a clue?
7. (Original post by Mr M)
Yes.

Isn't the pi and the absence of the degree symbol a bit of a clue?
I've never worked in radians before, but I'll be sure to remember that.
8. (Original post by ThatPerson)
I've never worked in radians before, but I'll be sure to remember that.
Oh. Well now you are out of short trousers you will be using radians all the time.
9. (Original post by Mr M)
Oh. Well now you are out of short trousers you will be using radians all the time.
Well, I can wait till September at least.

I'm still in short trousers.
10. (Original post by ThatPerson)
Well, I can wait till September at least.

I'm still in short trousers.
You will soon learn that

and

If you let then the result follows with no calculator required.

You just need to calculate the reciprocal of the square of one third minus one.

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Updated: March 15, 2013
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