The triangle is the strongest to as it holds it shape and has a base which is very strong a also has a strong support.
Yes, it is. The triangle is common in all sorts of building supports and trusses. It is strong because the three legs of a triangle define one and only one triangle. If all three sides are made of rigid material, the angles are fixed and cannot get larger or smaller without breaking at the joints, unlike a rectangle, for example, which can turn into a parallelogram and even collapse totally. If you take a rectangle and place one diagonal piece from corner to corner, you can make that strong and stable, too, but doing that makes two triangles!! Think about it! so yes, it is the strongest shape
The arc (think: circle) is the strongest structural shape, and in nature, the sphere is the strongest 3-d shape.
The reason being is that stress is distributed equally along the arc instead of concentrating at any one point.
Storage silos, storage tanks, diving helmets, space helmets, gas tanks, bubbles, planets, etc. use cylinder or sphere shapes -- or both.
The overall shape of many bridges is in the shape of a catenary curve.
The catenary curve is the strongest shape for an arch which supports only its own shape. Freely hanging cables naturally form a catenary curve.
NO, hexagons are the strongest shapes known.