How do you figure out the length of a right angle triangle if you already know the two dimensions that are the same? Say you want to build a shelf in the corner wall. You went 24" out from the corner on both sides. How do you figure out the other dimension? I can find the calculator but how do you figure it out? So I can do it on my calculator.
Can't find the formula. Can someone help me figure out this triangle
- Thread starter skipnay
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ddawg16
Well-known member
Google is your friend....(as long as politics are not involved)
http://www.calculator.net/triangle-calculator.html
http://www.calculator.net/triangle-calculator.html
ard
Well-known member
1.414 times 24 inches
The calculation: A**2 + B**2 = C**2; in your case A=B
Square root of (24 squared + 24 squared)
sqrt(24**2+24**2) = 33.94 inches
The calculation: A**2 + B**2 = C**2; in your case A=B
Square root of (24 squared + 24 squared)
sqrt(24**2+24**2) = 33.94 inches
onthefence777
Well-known member
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- Feb 19, 2012
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while that is a handy calculator, it is much simpler in this case than the trig there is.
with right triangles, its A(squared) + B(squared) = C(squared)
A and B are the distances you already knew, so it would be 24(squared) + 24(squared) = C(squared).
So [ (24)*(24) ] + [ (24)*(24) ] = C(squared)
In this case, you can do (24*24), and multiply that by two.
With the answer you get, use the square root function on your calculator, and that is the length of the hypotenuse (the length you don't know)
pancho400cid
Well-known member
As said - In the special case of the two "short" legs being equal, multiply by 1.41 (better known as the square root of 2 - approximate) to get the long leg (aka hypotenuse).... in other words the "1-1-SQRT 2" triangle
Another handy "special" case to remember is the 3-4-5 right triangle (leg A = 3 ft, leg B = 4 ft then longest leg is 5 ft).
The 1-1-SQRT 2 and 3-4-5 ratios apply for any length
13mm - 13mm - 18.38mm (1-1-SQRT 2)
9 in - 12 in - 15 in (3-4-5)
etc.
Another handy "special" case to remember is the 3-4-5 right triangle (leg A = 3 ft, leg B = 4 ft then longest leg is 5 ft).
The 1-1-SQRT 2 and 3-4-5 ratios apply for any length
13mm - 13mm - 18.38mm (1-1-SQRT 2)
9 in - 12 in - 15 in (3-4-5)
etc.
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theoldwizard1
Well-known member
Sorry, my OCD on math just kicked in.
A right triangle has one 90°. None of the sides are required to be of equal length. The side directly opposite of the angle is called the hypotenuse.
A triangle with 2 equal length sides is called a isosceles triangle.
Yes, you can have a right, isosceles triangle.
Yes, I was a geek before the word was even invented !
rarevair
Well-known member
Actually a right triangle with both legs equal is easy. Multiply the length of one side by the square root of 2. 1.41 might work . . . if you need more accuracy you can look up the square root of 2 to however many decimals as you need.
I use to be so good at math but nearing 40. Not using it much but a few adding, subtracting, multiplying, and maybe very little dividing has made me lose a lot of my math skills. The 1.414 is what I was looking for. Ok how do you do it when both sides are equal. Like 18"x26"=C Would be 324+676=1000squared. 1000 squared would be 31.622776602
Northislander
Well-known member
Do a google search for SOHCAHTOA everything you ever wanted to know about right angle triangles
csp
Well-known member
It's the pythagorean theorem.
matt_i
Well-known member
It would be 18^2 + 26^2 = 1000.
Now take the square root of 1000, or on your windows calculator, 1000^0.5
which equals the answer you gave of 31 5/8" since you are likely using a tape measure and not a CMM
rayra
Well-known member
Pythagorean Theorem.
You guys could complicate a free lunch.
You guys could complicate a free lunch.
dadsEH
Well-known member
Do it in mm. No need for a fractional outcome...lol
Westozfixer
Banned
Be careful saying that here you will get torched by the murica math clan.
Jon_E
Well-known member
Is that Common Core math?
BD1
Well-known member
Draw it out full size and measure .
lutter94
Well-known member
The Tool Tyrant
ALLIANCE MEMBER
aka Larry
Well-known member
You know there's a free app for solving right triangles right?
Brian_WK
Well-known member
Build it square then cut it in half. Voila 2 shelves!
Ya it got answered at least 18 times figured I would throw that out there A^2+B^2=C^2 is your answer.
Brian
Ya it got answered at least 18 times figured I would throw that out there A^2+B^2=C^2 is your answer.
Brian
kwoswalt99
Well-known member
See attached image.
4(1/2)ab+c^2=(a+b)^2
2ab+c^2=a^2+2ab+b^2
a^2+b^2=c^2
Complicated enough?
Yeah, it looks like this.
Attachments
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Outlander
Well-known member
I just posted in the old picture thread - maybe we should give this guy a high five
I also posted today in the younger generation thread. The old guy is turning over in his grave that us guys alive in 2017 don't run around quoting him daily.
Get off my toga, whippersnappers.
I also posted today in the younger generation thread. The old guy is turning over in his grave that us guys alive in 2017 don't run around quoting him daily.
Get off my toga, whippersnappers.
LS6 Tommy
Well-known member
American Carpenters don't need the metric system. They can actually READ a ruler...
Tommy
Sawdustmaker
Well-known member
Hey if it is not a right triangle and you know the angle between the two known sides you can use:
c^2=a^2+b^2-2abcosC (Law of Cosines)
c=missing side, a & b=known adjacent sides and C=measure of the included angle between the two known sides.
Is the Pythagorean Theorem with a correction for the angle not being a right angle. You will need a Trig Table (I don't think too many "young" people know what that is) or a calculator/Iphone (for those under age 60) to find cosC.
Sorry, couldn't help myself. Once a nerd, always a nerd.
c^2=a^2+b^2-2abcosC (Law of Cosines)
c=missing side, a & b=known adjacent sides and C=measure of the included angle between the two known sides.
Is the Pythagorean Theorem with a correction for the angle not being a right angle. You will need a Trig Table (I don't think too many "young" people know what that is) or a calculator/Iphone (for those under age 60) to find cosC.
Sorry, couldn't help myself. Once a nerd, always a nerd.
zeeway
Well-known member
Go hug your old high school math teacher is she is still around. Mine was Miss Hamlett, and she must be teaching math on the other side now,
RWorth
Well-known member
I see everyone was bored today.
