Results 1 to 5 of 5

Math Help - Isosceles Triangle

  1. #1
    Junior Member whytechocolate01's Avatar
    Joined
    Apr 2007
    From
    On A Cloud Over There Somewhere
    Posts
    46

    Exclamation Isosceles Triangle

    The legs of an isosceles triangle are 13 units long and the altitude to the base is 12 units long. What is the length of the base? How do you solve this?

    Thank you!!!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member
    earboth's Avatar
    Joined
    Jan 2006
    From
    Germany
    Posts
    5,830
    Thanks
    123
    Quote Originally Posted by whytechocolate01 View Post
    The legs of an isosceles triangle are 13 units long and the altitude to the base is 12 units long. What is the length of the base? How do you solve this?

    Thank you!!!
    Hello,

    the altitude divides the triangle into 2 right triangles. The legs of the isosceles triangle are the hypotenuses of the 2 right triangles and x is half of the base and it is one leg of a right triangle.
    Now use Pythagorean theorem:
    13 = 12 + x ==> x = 25 ==> x = 5

    Therefore the base is 10 units long.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    is up to his old tricks again! Jhevon's Avatar
    Joined
    Feb 2007
    From
    New York, USA
    Posts
    11,663
    Thanks
    3
    Quote Originally Posted by whytechocolate01 View Post
    The legs of an isosceles triangle are 13 units long and the altitude to the base is 12 units long. What is the length of the base? How do you solve this?

    Thank you!!!
    again, we form two right angled triangles and again we will use Pythagoras' theorem (do you know the theorem?)

    for one of the triangles we would have the base unknown, the height = 12 and the hypotenuse = 13. use Pythagoras' theorem to find the base. this base will be half the base of the whole tirangle, so just multiply the answer by 2 and there you have it
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Junior Member whytechocolate01's Avatar
    Joined
    Apr 2007
    From
    On A Cloud Over There Somewhere
    Posts
    46
    This is what I got...

    13 sqrd. = 12 sqrd. + x sqrd

    x sqrd = 25

    x = 5

    Therefore the base = 10

    Correct?
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Bar0n janvdl's Avatar
    Joined
    Apr 2007
    From
    Meh
    Posts
    1,630
    Thanks
    6
    Yes the total length of the base is 10.

    Therefore you are 100% correct
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. value of x in an isosceles triangle
    Posted in the Trigonometry Forum
    Replies: 1
    Last Post: April 6th 2011, 09:43 AM
  2. Isosceles triangle
    Posted in the Trigonometry Forum
    Replies: 3
    Last Post: February 28th 2010, 06:44 AM
  3. isosceles triangle
    Posted in the Geometry Forum
    Replies: 1
    Last Post: December 6th 2008, 01:54 PM
  4. Isosceles triangle
    Posted in the Geometry Forum
    Replies: 1
    Last Post: November 11th 2008, 10:41 AM
  5. Replies: 27
    Last Post: April 27th 2008, 11:36 AM

Search Tags


/mathhelpforum @mathhelpforum