Ok, so:
Let me draw something here below:
So, this is an equilateral triangle.
a. An equilateral triangle has the same lenght for its three sides.
For this reason, the measure of all its angles is 60°.
b. Let me draw the situation below:
We can fit 6 equilateral triangles together at one vertex, as you can see in the figure.
c. As we can see in the upper figure, these 6 triangles form a hexagon as an outside shape.
