Equivalent Diameter

Just convert the area of the square or triangle into the area of a circle.

The formula can be found in your textbook, or the internet, by searching for it.

Is the equivalent diameter is same, when the circle, square,and triangle shapes have the same cross section area?

Definitely not.

If you take a right triangle with equal base and altitude of say 15 units, then its circumdiameter will be 21.2 units and its CSA will be 112.5 units².

A square of the same edge measurements and therefore the same circumdiameter will have a CSA of exactly twice that at 225 units².

A circle of the same diameter would have a CSA of 353 units².

diameter of square and triangle??????????????????

Equivalent in what regards:

Same perimeter?

Same area?

Same torsional moment of inertia?

Same bending moment of inertia?

Same . . . . . ?

Member kahaten suffers from "Lazy Student Syndrome".

If you know my situation you will give more respect

Please tell us your situation.

Please don't.

Are you the teacher ?

The people Engineers that contribute to this forum have a combined education and work experience in the hundreds of years of expert knowledge.

I remember when I was in my first workplace, I was told:

1. Sit down!
2. Shut up!
3. Listen!
4. Do as we say!
5. Don't get hurt!
6. Pick up that broom and shovel!
7. Do you know how to use those tools? Yes!
8. Now! Go to work!

Was it a harsh wake up call? YES! But these Professionals took the time to train me when I listened to them and showed interest in solving the issue at hand. They have seen a lot of successes and probably many more failures, but they learned from their mistakes and imparted that knowledge to me and others that were / are willing to listen and try!When I made a mistake, they asked me to find the cause of the mistake.

1. Did I do as they said? NO
2. Did I ask a question before I made the mistake? NO
3. Did I follow directions? NO
4. Should I have? YES

Good luck!

JE JE
The mathematical proof that the quadrature of the circle is impossible using only compass and straightedge has not proved to be a hindrance to the many people who have invested years in this problem anyway. Having squared the circle is a famous crank assertion. (See also pseudomathematics.) In his old age, the English philosopher Thomas Hobbes convinced himself that he had succeeded in squaring the circle

I assume that you are referring to the circumdiameter or circumcircle here.

If so, then the answer will depend on whether the triangle is a right triangle or not.

If it is a right triangle, then its circumdiameter will be equal to the length of its hypotenuse.

If it is an equilateral triangle then the circumdiameter can be found by dividing the length of one side by root three.

Other triangles become a little more complex depending on what information you have.

To find the circumdiameter of a square or oblong, simply treat it as a right triangle and calculate the length of the hypotenuse using Pythagorus' theorum.

Your reply is very useful,but I have one question about triangle

I've equilateral triangle with 6.75mm length. did you mean D_equ.=6.75/cuberoot(3)?.

sorry, I've some problems in my English.

No...The square root of 3.

Upon re-reading what I said in #6, I stated:- "If it is an equilateral triangle then the circumdiameter can be found by dividing the length of one side by root three".

I should have said "If it is an equilateral triangle then the circumdiameter can be found by dividing the length of one side by root three and then multiplying by 2".

For your example - an equilateral triangle with sides of 6.75mm will have a circumdiameter = (6.75/√3) X 2 = (6.75/1.732) X 2 = 3.897 X 2. Therefore the circumdiameter will be 7.794mm

Its CSA will be found by the formula CSA = (√3 / 4) X length of one side² = 19.73mm²

Thank you so much

Circumdiameter is irrelevant to this problem. Several smaller diameters might be relevant, depending on criteria. (Moment of inertia is probably, but not necessarily, the most salient.)

If you're talking about hydraulics, equivalent diameter = 4*cross-section area/wetted perimeter. So for circular pipe diameter D, D_h = 4*pi*D²/(4*pi*D) = D. For square pipe side L, D_h = 4*L²/(4*L) = L. For a triangular pipe it depends on the shape.