I've attached a picture that pertains to the query that I have. I have been able to show that each angle B is 60 degrees, but I am unsure as to how to show a is also a 60 degree angle. Isn't there some geometric theorem I could use?
All right, so I know that each angle is equivalent to each other, when you consider one single triangle. Is this sufficient to show that it must be a equilateral triangle, or must I also so that each side has the same length?