Answer :
A plane of symmetry is a hypothetical plane that divides an object into two mirror-image halves. We'll compare the planes of symmetry for a regular pentagonal prism and a regular triangular prism.
First, let's consider a regular pentagonal prism:
1. By definition, a regular pentagonal prism has a regular pentagon as its base. A regular pentagon has 5 lines of symmetry, each passing through a vertex and the midpoint of the opposite side.
2. In addition, a regular pentagonal prism can have one plane of symmetry that bisects the prism through its length, essentially dividing it into two congruent halves with pentagonal faces facing each other.
Therefore, a regular pentagonal prism has 5 (from the pentagon base) + 1 (through its length) = 6 planes of symmetry.
Now, let's look at a regular triangular prism:
1. A regular triangular prism has a regular triangle (equilateral triangle) as its base. A regular triangle has 3 lines of symmetry, each passing through a vertex and the midpoint of the opposite side.
2. Similarly, a regular triangular prism can have one plane of symmetry that bisects the prism through its length, dividing it into two congruent halves with triangular faces facing each other.
So, a regular triangular prism has 3 (from the triangle base) + 1 (through its length) = 4 planes of symmetry.
To find out how many more planes of symmetry the regular pentagonal prism has compared to the regular triangular prism, we calculate the difference:
6 (planes of symmetry, pentagonal prism) - 4 (planes of symmetry, triangular prism) = 2.
Therefore, a regular pentagonal prism has 2 more planes of symmetry than a regular triangular prism.