Triangle Help

**lizann** · May 25th 2008, 03:36 PM

Hello my name is elizabeth or liz and I need some help in my math. If there is anyone that can help me please let me know. Here is a first problem just in case: What does it mean to refer to a 20-in tv set or a 25-in tv set? Such units refer to the diagonal of the screen. A 10-in tv set also has a width of 8 inches. What ia it's height?

**thelostchild** · May 25th 2008, 03:54 PM

you can find the height using Pythagorus. If you think of the TV screen as a rectangle, cut that rectangle in half from one corner to another.

You would then have a right angled triangle, the diagonal of that would be the hypotenuse which is given(10 inches) the width would be one of the other two sides (8 inches) The height would be the remaining side which we can find using Pythagorus

$a^2+b^2=c^2$
we know the hypotenuse is 10 so therefore c=10 and one side is 8 so say a=8 and we want to find b (which would be the height)

rearranging that we have
$b=\sqrt{c^2-a^2}$
so
$b=\sqrt{10^2-8^2}=\sqrt{36}=6$

**TheEmptySet** · May 25th 2008, 03:55 PM

Here is a diagram.

P.S always draw a picture

They want us to find the height of the T.V.

We notice that the diagonal cuts the rectangle into two right triangles.

Since we have right triangles we can use the pythagorean theorem to find the missing side.

$a^2+b^2=c^2$

Where c is the length of the hypotenuse ( the diagonal of the rectangle)

$8^2+h^2=10^2 \iff 64+h^2=100 \iff h^2 =36 \iff h=6$

So the height of the T.V. is 6 inches.

I hope this helps.

**lizann** · May 25th 2008, 04:42 PM

Thank you both for the help I really appreciate it.

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Triangle Help

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