Prove Quadrilateral ABCD Perimeter $\geq (4+2\sqrt 2)S$

MHB
Thread starter Albert1
Start date Dec 16, 2016
Tags

Convex

In summary, the statement is trying to prove that the perimeter of Quadrilateral ABCD is greater than or equal to (4+2√2)S. This can be done by using the Pythagorean theorem and properties of right triangles or by using the properties of convex quadrilaterals and the Triangle Inequality Theorem. The number (4+2√2) is significant because it represents the sum of the diagonals of a square with side length S. This statement can be proven for any convex quadrilateral, and it could be useful in engineering or construction to ensure safety or stability. There are also other equivalent statements that could be used to prove the same concept, such as the fact that the perimeter of a square is

Dec 16, 2016

Albert1

A convex quadrilateral ABCD with area $S^2$ , prove the sum of its perimeter and two diagonal lines $\geq (4+2\sqrt 2)S$

Last edited: Dec 16, 2016

Mathematics news on Phys.org

Dec 19, 2016

Albert1

Albert said:

A convex quadrilateral ABCD with area $S^2$ , prove the sum of its perimeter and two diagonal lines $\geq (4+2\sqrt 2)S$

hint:

$Use\,\,area\,\,of \,\,a\,\,triangle=\dfrac {bc\,sin \,A}{2}=---,and\,\, AP\geq GP$

1. How do you prove that the perimeter of Quadrilateral ABCD is greater than or equal to (4+2√2)S?

There are a few ways to prove this statement. One approach would be to use the Pythagorean theorem and the properties of right triangles to show that the length of each side of the quadrilateral is greater than or equal to (2+√2)S. Another approach would be to use the properties of convex quadrilaterals and the Triangle Inequality Theorem to show that the perimeter must be greater than or equal to (4+2√2)S.

2. What is the significance of the number (4+2√2) in this statement?

The number (4+2√2) is the sum of the lengths of the diagonals of a square with side length S. This means that the statement is essentially saying that the perimeter of Quadrilateral ABCD must be greater than or equal to the perimeter of a square with side length S.

3. Can this statement be proven for any type of quadrilateral, or only for specific types?

This statement can be proven for any convex quadrilateral, as long as it is not degenerate (meaning it has a zero area). This includes rectangles, squares, parallelograms, and trapezoids, among others.

4. Is there a specific application or real-world scenario where this statement would be useful?

This statement could be useful in engineering or construction, where it may be necessary to ensure that a quadrilateral-shaped structure has a perimeter that is at least a certain length in order to meet safety or stability requirements.

5. Are there any other equivalent statements to this one that could be used to prove the same concept?

Yes, there are other equivalent statements that could be used to prove this concept. For example, instead of using the length of the diagonals of a square, one could use the fact that the perimeter of a square is always greater than or equal to four times its side length. This would result in a statement like "The perimeter of Quadrilateral ABCD is greater than or equal to 4S."