SOLUTION: the hypotenuse of a right triangle is 12 inches and the area is 24 square inches. Find the dimension of the triangle, correct to one decimal place.

Algebra ->  Formulas -> SOLUTION: the hypotenuse of a right triangle is 12 inches and the area is 24 square inches. Find the dimension of the triangle, correct to one decimal place.      Log On


   



Question 1041173: the hypotenuse of a right triangle is 12 inches and the area is 24 square inches. Find the dimension of the triangle, correct to one decimal place.
Found 3 solutions by josgarithmetic, ikleyn, MathTherapy:
Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
x y h dimensions; h for hypotenuse

system%28x%5E2%2By%5E2=12%5E2%2Cxy=24%29

y=24%2Fx
-
x%5E2%2B%2824%2Fx%29%5E2=144
x%5E4%2B24=144x%5E2
x%5E4-144x%5E2%2B24=0
Solve first for x%5E2....

Graphing y=x^4-144x^2+24 through google.com shows that there are three real and apparently rational roots, so that degree-four polynomial is factorable.

Answer by ikleyn(52786) About Me  (Show Source):
You can put this solution on YOUR website!
.
The hypotenuse of a right triangle is 12 inches and the area is 24 square inches.
Find the dimension of the triangle, correct to one decimal place.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

x%5E2+%2B+y%5E2 = 12%5E2,       (1)
%281%2F2%29%2Axy  = 24,       (2)

or

x%5E2+%2B+y%5E2 = 144,        (1')
xy     = 48.         (2')

Multiply eqn. (2') by 2 and add to eqn(1') (both sides). You will get

x%5E2+%2B+2xy+%2B+y%5E2 = 144+%2B+2%2A48,   or

%28x%2By%29%5E2 = 240,   or

x%2B+y = sqrt%28240%29 = 4%2Asqrt%2815%29.

Thus from (1) and (2) we got 

x + y = 4%2Asqrt%2815%29,         (3)
xy    = 48.             (4)

   Notice that in this way we decreased the degree of the original equations/system.

   It makes it easier to work in future with (3),(4) instead of (1),(2).


Next, from (3)  x = 4%2Asqrt%2815%29+-+y. Substitute it into (4) and get

%284%2Asqrt%2815%29-y%29%2Ay = 48.     (5)

y%5E2+-+%284%2Asqrt%2815%29%29%2Ay+%2B+48 = 0,

Solve this quadratic equation by applying the quadratic formula. You will get

y%5B1%2C2%5D = %284%2Asqrt%2815%29+%2B-+sqrt%28240-4%2A48%29%29%2F2 = %284%2Asqrt%2815%29+%2B-+sqrt%2848%29%29%2F2 = 2%2Asqrt%2815%29+%2B-+2%2Asqrt%283%29.

Then x%5B1%2C2%5D = 4%2Asqrt%285%29 - %282%2Asqrt%2815%29+%2B-+2%2Asqrt%283%29%29.

Answer. There are two solutions:

        a)  x = 2%2Asqrt%2815%29-2%2Asqrt%283%29,  y = 2%2Asqrt%2815%29+%2B+2%2Asqrt%283%29,  and

        b)  x = 2%2Asqrt%2815%29%2B2%2Asqrt%283%29,  y = 2%2Asqrt%2815%29+-+2%2Asqrt%283%29.

Check.  a) x%5E2+%2By%5E2 = 4%2A15+%2B+4%2A3+%2B+4%2A15+%2B+4%2A3 = 144,  xy = 4*15 - 4*3 = 60 - 12 = 48.   OK ! ! !


Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!
the hypotenuse of a right triangle is 12 inches and the area is 24 square inches. Find the dimension of the triangle, correct to one decimal place.
Height and base: highlight_green%28matrix%281%2C7%2C+11.2%2C+and%2C+4.3%2C+or%2C+4.3%2C+and%2C+11.2%29%29