Results 1 to 6 of 6

Math Help - problems with quite a few questions

  1. #1
    Member
    Joined
    Sep 2005
    Posts
    84

    problems with quite a few questions

    hello.

    as part of my revision i carried many questions at home. these are questions which i couldn't answer and wasn't able to find the solutions from textbooks.

    all your help is appreichated.

    i have attached the questions.

    thank you

    regards

    Attached Thumbnails Attached Thumbnails problems with quite a few questions-problemsnew1.jpg   problems with quite a few questions-gdfgfdrtt45.jpg  
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Oct 2005
    From
    Earth
    Posts
    1,599
    I'll start with #8. Area is measured in two dimensions, so you know that it is going to reduce down to some form of l x w, or length times width. So for instance take the surface area of a sphere, 4\pi{r^2}. You can see that the term r squared implies two demensions and the formula makes sense in that aspect. Two of your expressions are expressed in this basic form, with constants thrown in that won't affect them in making them an area.
    Last edited by Jameson; November 25th 2005 at 08:14 PM.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Grand Panjandrum
    Joined
    Nov 2005
    From
    someplace
    Posts
    14,972
    Thanks
    4
    I'll continue with #18.

    The two cylinders are similar, which means that they have the
    same proportions but different sizes. The surface areas of similar
    solids scale as the square of the ratio of corresponding linear
    dimensions. Thus if our cylinders had heights of 6 and 12 cm the
    surface area of the larger would be four times that of the smaller.

    The volumes of similar solids scale as the cube of the ratio of
    corresponding linear dimensions. Thus if our cylinders had heights
    of 6 and 12 cm the volume of the larger would be eight times
    that of the smaller.

    So if C1 and C2 are our two cylinders we have:

    \mbox{SurfArea}(C1)/\mbox{SurfArea}(C2)\ =\ [\mbox{Height}(C1)/\mbox{Height}(C2)]^2.
    \mbox{Volume}(C1)/\mbox{Volume}(C2)\ =\ [\mbox{Height}(C1)/\mbox{Height}(C2)]^3.


    With this the solution of #18 should be easy.

    RonL
    Last edited by CaptainBlack; November 26th 2005 at 12:17 AM.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Grand Panjandrum
    Joined
    Nov 2005
    From
    someplace
    Posts
    14,972
    Thanks
    4
    Continuing with #11.

    This is about the properties of similar triangles - Since QT parallel to
    RS implies that triangle PQT is similar to triangle PRS.

    a) Hence from the properties of ratios of corresponding sides of similar
    triangles we may conclude:
    \frac{PQ+QR}{PQ}\ =\ \frac{PS}{PT},
    which will allow you to find QR.

    b) Similarly we have::
    \frac{QT}{SR}\ =\ \frac{PT}{PS},
    which will allow you to find QT.

    RonL
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Grand Panjandrum
    Joined
    Nov 2005
    From
    someplace
    Posts
    14,972
    Thanks
    4
    Moving on to #22.

    What you need to know to do this problem is that in any
    polygon with vertices V_1,\ V_2,\ ...\ V_n, that:
    \vec{V_1V_2}+\vec{V_2V_3}+\ ...\ +\ \vec{V_{n-1}V_n}\ =\ 0.

    and that for two segments AB and CD to be
    parallel means that for some real number k:
    \vec{AB}\ =\ k.\vec{CD}.

    RonL
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Member
    Joined
    Sep 2005
    Posts
    84
    thank you !!!!
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Problems solving some inequalities questions
    Posted in the Algebra Forum
    Replies: 9
    Last Post: March 29th 2011, 02:39 PM
  2. parabola problems, and other questions
    Posted in the Algebra Forum
    Replies: 12
    Last Post: February 5th 2010, 09:18 AM
  3. TI-84 Problems & Questions - Urgent
    Posted in the Calculators Forum
    Replies: 0
    Last Post: March 12th 2009, 06:16 PM
  4. Questions about Optimization Problems
    Posted in the Calculus Forum
    Replies: 4
    Last Post: November 19th 2007, 04:35 AM

Search Tags


/mathhelpforum @mathhelpforum