Can someone help me in b please

Equilateral trianglesEquilateral triangles have sides of all equal length and angles of 60°. To find the height, we can draw an altitude to one of the sides in order to split the triangle into two equal 30-60-90 triangles. Now, the side of the original equilateral triangle (lets call it "a") is the hypotenuse of the 30-60-90 triangle.

Need more information to solve it