Results 1 to 2 of 2

Math Help - help about right triangles!

  1. #1
    Newbie
    Joined
    Nov 2010
    Posts
    5

    help about right triangles!

    hello!

    i have question about right triangles and perimeter:

    "If the perimeter of a right triangle is 12 and it's hypotenuse is 5, what is the area of the triangle?"

    formula for area: a=bh/2

    perimeter = b+h+hypotenuse = 12

    this is solved by substitution?

    b+h+5=12
    b+h=7
    b=7/h

    a=bh/2

    a=[(7/h)h]/2

    a=7/2

    a=3.5
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor MarkFL's Avatar
    Joined
    Dec 2011
    From
    St. Augustine, FL.
    Posts
    1,988
    Thanks
    734

    Re: help about right triangles!

    Let a and b be the two legs of the right triangle. Since the perimeter is 12 and the hypotenuse is 5, we know:

    a+b=7

    By the Pythagorean theorem, we also know:

    a^2+b^2=5^2

    I recommend squaring the first equation to find ab, since the second equation gives you the value of the sum of the squares of the legs.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 3
    Last Post: March 19th 2011, 04:42 AM
  2. How many triangles?
    Posted in the Geometry Forum
    Replies: 7
    Last Post: July 30th 2010, 12:13 PM
  3. triangles
    Posted in the Geometry Forum
    Replies: 1
    Last Post: November 18th 2009, 08:46 AM
  4. sin and cos and triangles oh my
    Posted in the Trigonometry Forum
    Replies: 7
    Last Post: January 21st 2008, 07:55 PM
  5. Triangles
    Posted in the Geometry Forum
    Replies: 1
    Last Post: December 9th 2007, 09:17 AM

Search Tags


/mathhelpforum @mathhelpforum