Please Help (math)

Since it is an equilateral triangle, each of the interior angles is 60^o.

 

Look at the large triangle  -- from the center of the circle to the point of tangency to the exterior vertex.

The angle formed by the radius and the tangent is 90^o.

The angle at the center of the circle is 60^o.

Therefore, angle(x) is 30^o.

 

I can't draw on this site, or I'd label the diagram.  I'll try to explain it with words. 

 

The inside triangle is equilateral so all its angles are 60^o  

 

On the right of the diagram,

the angle of the outside triangle is supplemental to 60^o so it's 120^o  

 

On the left of the diagram,

the tangent is perpendicular to the radius,so the supplemental angle of the outside triangle is 90^o – 60^o = 30^o 

 

The sum of those two angles is 150^o.  All the angles of any triangle total 180^o so x is 180^o – 150^o = 30^o  

_.