Final answer:
A triangle with 0 reflectional symmetries is a scalene triangle. Equilateral triangles, such as those on an icosahedron, have multiple symmetries. Symmetry in different contexts, like physics and chemistry, can result in a net effect of zero.
Step-by-step explanation:
A triangle that has 0 reflectional symmetries is a scalene triangle, where all three sides and all three angles are of different lengths and magnitudes, respectively. An equilateral triangle, like the ones that form the faces of an icosahedron, has multiple lines of symmetry because of its equal sides and angles. On another note, in vector algebra, a null vector has all components equal to zero, which implies it has no direction or magnitude. Similarly, the molecular geometry of BF3 is described as trigonal planar and possesses symmetry, resulting in a net dipole moment of zero despite having polar B-F bonds.
In physics-related symmetry, charges or forces can cancel each other out leading to a net force of zero. For instance, if equal charges are placed at the corners of a square with a charge at the center, the net Coulomb force on the center charge will be zero due to the symmetry. Similarly, in collisions, certain angles or scenarios can result in a term becoming zero, like having a head-on collision where the incoming ball stops (v1 = 0), or the balls deflect at a 90-degree angle resulting in cos(θ1 - θ2) being zero.