Question

Link is coloring a triforce, which consists of four equilateral triangles and is depicted below. He has three colors to use: gold, black, and green. So that it remains recognizable, he doesn't want to color any two triangles the same color if they share a side. How many different ways can he color the triforce? (Two colorings that differ by rotation are considered distinct.)

Answer 1

24

Explanation:

We first choose a center triangle. There are three ways to do that. Then, we choose the outer ones, which has 2 colors to choose from. The answer is 3*2*2*2=24

Answer 2

12

Explanation:

For the top triangle, he has 3 options

3C1 = 3

For the middle one, he can't use the top triangle's colour, so 2 options

2C1 = 2

For the ones on sides of the middle one, 2 options each

2C1 × 2C1 = 4

3 × 2 × 2 × 2 = 24

These include all three outer ones same, so subtract 3

Also, these include 2 of the three outer ones same, so subtract:

3C2 × 3 = 9

24 - 3 - 9 = 12