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#1 2006-12-21 04:20:38

Kiran
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Registered: 2006-11-15
Posts: 177

Triangle

solve for x and y
                 
                     *
                  * y  *
                *  dg    *
  8          *               *    10
            *                    *
          *                         *
        *                              *
      *                                   *
    *                                        *
  *                                              *
*   x degrees                                   *
********************************
                      11

I did .. but i need your help!

p^2 = a^2 + b^2 - 2ab cos P
8^2 = 10^2 + 11^2 - 2 (10)(11) cos X
64 = 100 + 121 - 220 cos X
64 = 221 - 220 - cos X
221 - 64 = 157
157 = 220 cos X
0.7 = cos X
how many degrees is that?

and i know i have ot do this when i find teh degrees .....
to find y

8/sin(x) = 11/sin y

sin y = 11sin(x)/8

sin y = ________
and how much degrees is that?


PELASE HELP ME OUT

Last edited by Kiran (2006-12-21 05:20:55)


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#2 2006-12-21 04:36:46

Stanley_Marsh
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Registered: 2006-12-13
Posts: 345

Re: Triangle

I think the p should be 10 , since the length p shoudn't be the adjacent  to angle x

Last edited by Stanley_Marsh (2006-12-21 04:38:03)


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#3 2006-12-21 04:56:02

Kiran
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Registered: 2006-11-15
Posts: 177

Re: Triangle

well i dont know...thats how they did it in the book


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#4 2006-12-21 05:10:51

Stanley_Marsh
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Registered: 2006-12-13
Posts: 345

Re: Triangle

Is the length of the third side 11? is it given?


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#5 2006-12-21 05:21:12

Kiran
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Registered: 2006-11-15
Posts: 177

Re: Triangle

oh god yeha..i forgot to put 11........thanks for reminding me

Last edited by Kiran (2006-12-21 05:21:50)


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#6 2006-12-21 05:22:15

Kiran
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Registered: 2006-11-15
Posts: 177

Re: Triangle

can you help me out please?!


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#7 2006-12-21 05:29:08

Stanley_Marsh
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Registered: 2006-12-13
Posts: 345

Re: Triangle

well   follow the equality 
10^2=8^2+11^2 - 2x8x11cosx
cosx=85/176

11^2=8^2+10^2-8x10x2cosy
cosy=43/160

That's my solution , Don't know if I am correct


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#8 2006-12-21 08:14:26

Kiran
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Registered: 2006-11-15
Posts: 177

Re: Triangle

ok in my book  they have the exact same question but offcourse with different numbers.
now i dont understand if we have such as in the book they have 0.5=cos x
and they said x = 60 degrees , 300 degrees and then they said x is less than 90 degrees so x = 60 degrees

how can i find the degrees of my problem?


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#9 2006-12-21 08:19:09

luca-deltodesco
Member
Registered: 2006-05-05
Posts: 1,470

Re: Triangle

if you have


then you rearrange by taking the inverse cosine of both sides

or if you are in america

Last edited by luca-deltodesco (2006-12-21 08:19:42)


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#10 2006-12-21 08:24:33

Kiran
Member
Registered: 2006-11-15
Posts: 177

Re: Triangle

ok guys i dont know...
can you show me what you might think will be the way in solving the problem?


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#11 2006-12-21 16:04:07

Stanley_Marsh
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Registered: 2006-12-13
Posts: 345

Re: Triangle

The value of 0 dg , 30dg , 45dg , 90dg  must be remembered , or you can draw a coordinate graph of triangle function or an acute triangle to find these values.


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