Math Is Fun Forum

EbenezerSon

Member

Registered: 2013-07-04

Posts: 554

Finding the length

Hi;
Please help me with this;

The area of a right angled triangle is 50cm^2. One of its angler is 45°. Find, correct to one decimal place, the length of the longest side(hypotenuse)

Many thanks

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I know only one thing - that is that I know nothing

Bob

Administrator

Registered: 2010-06-20

Posts: 10,619

Re: Finding the length

hi EbenezerSon

If it is right angled and has an angle of 45, then the third angle must also be 45.  So it is isosceles with equal shorter sides.

area = half base times height, so you can work out the base and height (equal).

And the Pythagoras will give the hypotenuse.

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

EbenezerSon

Member

Registered: 2013-07-04

Posts: 554

Re: Finding the length

Then please, check for me;
If issosceles then;

2x = 180
x = 180/2
x = 90

Is both length calculations correct?

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I know only one thing - that is that I know nothing

Bob

Administrator

Registered: 2010-06-20

Posts: 10,619

Re: Finding the length

Whoops, no.

The triangle is isosceles with angles 90 45 and 45

Let's call the sides base = height and hypotenuse.

area = half base x height = 50 so base x height = 100 so base = height = 10

so hypotenuse^2 = 10^2 + 10^2

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

EbenezerSon

Member

Registered: 2013-07-04

Posts: 554

Re: Finding the length

Many thank Bob, but see this;

(1) A rectangular garden has 24m fence surrounding its. Find the dimension of the plot if its area is 27m^2.

I have dealt with it and I had 3 as width and 9 as the lenght, please confirm-
Thank you.

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I know only one thing - that is that I know nothing

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: Finding the length

Hi;

Could be the other way around but the lengths of 9 and 3 are correct.

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.