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#1 2006-11-12 11:38:31

girlnamedfreak
Member
Registered: 2006-11-12
Posts: 7

two trig questions

how can i estimate the sine or tangent in a given triangle




and why is the sine of the 30 degrees equal to .5?






thanks

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#2 2006-11-12 12:48:52

mathsyperson
Moderator
Registered: 2005-06-22
Posts: 4,900

Re: two trig questions

Your second question is answered about halfway down this page.

The first question is a bit more abstract. Could you elaborate a bit on what you mean, please?


Why did the vector cross the road?
It wanted to be normal.

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#3 2006-11-12 14:56:24

girlnamedfreak
Member
Registered: 2006-11-12
Posts: 7

Re: two trig questions

the exact question on my homework is: Estimate sinA and tanB in the given triangle ABC

then theres a picture of a right triangle thats labeled with A, B, and C and the 90 degree angle is shown

thats all it says and we never went over anything like this in class so I have no clue what to do

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#4 2006-11-12 16:42:22

MathsIsFun
Administrator
Registered: 2005-01-21
Posts: 7,552

Re: two trig questions

So maybe you could try to measure angle A (or B). If A is 30 degrees, then you can answer with sin 30 (=0.5), and tan 60 (=√3) (because if A is 30, B has to be 60).

If angle A is something else, maybe you could use your calculator smile


"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

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#5 2006-11-12 22:21:07

mathsyperson
Moderator
Registered: 2005-06-22
Posts: 4,900

Re: two trig questions

Or, because it's a right-angled triangle, then a possible simpler way would be to measure the sides of the triangle and find their ratios.

   A
   |\
   |  \
   |    \   c
b |      \
   |        \
   |          \
C ----------- B
         a

Sin A in this case would be length a divided by length c, and tan B would be b divided by a.

That might change depending on which angle is the right angle though.


Why did the vector cross the road?
It wanted to be normal.

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