Results 1 to 2 of 2

Thread: 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
    2,005
    Thanks
    747

    Re: help about right triangles!

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

    $\displaystyle a+b=7$

    By the Pythagorean theorem, we also know:

    $\displaystyle a^2+b^2=5^2$

    I recommend squaring the first equation to find $\displaystyle ab$, 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: Mar 19th 2011, 04:42 AM
  2. How many triangles?
    Posted in the Geometry Forum
    Replies: 7
    Last Post: Jul 30th 2010, 12:13 PM
  3. triangles
    Posted in the Geometry Forum
    Replies: 1
    Last Post: Nov 18th 2009, 08:46 AM
  4. sin and cos and triangles oh my
    Posted in the Trigonometry Forum
    Replies: 7
    Last Post: Jan 21st 2008, 07:55 PM
  5. Triangles
    Posted in the Geometry Forum
    Replies: 1
    Last Post: Dec 9th 2007, 09:17 AM

Search Tags


/mathhelpforum @mathhelpforum