Apyramid has all side that are equilateral triangles. each triangle has side lengths of 11 cm. if the surface area of the pyramid is 330 square centimeters, what is the slant height of the pyramid?

This is the concept of geometry, we are required to get the slant height of the pyramid which has been formed by equilateral triangles;
Here we shall use the pythagorean theorem;
c^2=a^2+b^2
the slant side is the height of the pyramid, the side length is one of the hypotenuse thus, hypotenuse=11 cm, 
the length of the slant height will be:
11^2=(11/2)^2+b^2
b^2=121-(11/2)^2
b^2=90.75
thus;
b=sqrt(90.75)
b=9.53 cm

The answer is, slant height will be 9.53 cm