Results 1 to 6 of 6

Math Help - newbies need sum help..

  1. #1
    Newbie jhaycianofficial's Avatar
    Joined
    Jan 2013
    From
    manila
    Posts
    8

    newbies need sum help..

    hi im engr. Student.. H0pe u help me with this .. Can any0ne s0lve this using law 0f c0sine: (my pr0f. Said that it can be d0ne by the said law)1. If the sl0wer ship in the preseding exercise leaves at noon, and the other at 1p.m., how far apart are they at 2p.m.?2.three circles 0f radii 3,4,and 5 inches respectively are tangent t0 each 0ther externally. Find the angles 0f the triangle f0rmed by j0ining the centers.Can any give the s0luti0n with figure s0 i will understand it .. Tnx in advance )
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor ebaines's Avatar
    Joined
    Jun 2008
    From
    Illinois
    Posts
    1,113
    Thanks
    325

    Re: newbies need sum help..

    For the first problem you've left out some critical data - such as the speed of the two boats - so it's impossible to answer as written.

    For the 2nd you know that the 3 sides of the triangle are lengths 7, 8, and 9 - do you see what that is? Now apply the law of cosines:

     C^2 = A^2 + B^2 - 2AB \cos(c)

    You have values for A, B and C, so solve for  \cos(c) and hence the angle 'c'. Repeat for angle 'b', and angle 'a' is 180 degrees - c - b.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie jhaycianofficial's Avatar
    Joined
    Jan 2013
    From
    manila
    Posts
    8

    Re: newbies need sum help..

    For the 2nd you know that the 3 sides of the triangle are lengths 7, 8, and 9 - do you see what that is? Now apply the law of cosines:  C^2 = A^2 + B^2 - 2AB \cos(c) You have values for A, B and C, so solve for  \cos(c) and hence the angle 'c'. Repeat for angle 'b', and angle 'a' is 180 degrees - c - b.[/QUOTE] CanU please figure it out .. how it the 3 sides became 7,8,9 ?? can u give the figure?
    Last edited by jhaycianofficial; January 19th 2013 at 05:11 PM. Reason: [SOLVED]
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Newbie jhaycianofficial's Avatar
    Joined
    Jan 2013
    From
    manila
    Posts
    8

    Re: newbies need sum help..

    Quote Originally Posted by ebaines View Post
    For the first problem you've left out some critical data - such as the speed of the two boats - so it's impossible to answer as written.

    For the 2nd you know that the 3 sides of the triangle are lengths 7, 8, and 9 - do you see what that is? Now apply the law of cosines:

     C^2 = A^2 + B^2 - 2AB \cos(c)

    You have values for A, B and C, so solve for  \cos(c) and hence the angle 'c'. Repeat for angle 'b', and angle 'a' is 180 degrees - c - b.
    Two ships leave a dock at the same time. One sails northeast at the rate 8.5 km/hr. The other sails north at a rate 10 km./hr. how far APART are they at the end of two hours.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Newbie jhaycianofficial's Avatar
    Joined
    Jan 2013
    From
    manila
    Posts
    8

    Re: newbies need sum help..

    Quote Originally Posted by jhaycianofficial View Post
    Two ships leave a dock at the same time. One sails northeast at the rate 8.5 km/hr. The other sails north at a rate 10 km./hr. how far APART are they at the end of two hours.
    oh im so sorry ..the preceding exercise is THAT !
    Follow Math Help Forum on Facebook and Google+

  6. #6
    MHF Contributor ebaines's Avatar
    Joined
    Jun 2008
    From
    Illinois
    Posts
    1,113
    Thanks
    325

    Re: newbies need sum help..

    Quote Originally Posted by jhaycianofficial View Post
    CanU please figure it out .. how it the 3 sides became 7,8,9 ?? can u give the figure?
    If you draw two circles that are tangent to each other (the circles are just touching) you can see that the distance between the centers of the two circles is equal to the sum of their radii.
    Follow Math Help Forum on Facebook and Google+

Search Tags


/mathhelpforum @mathhelpforum