Question 1093664
The description is of a special 30-60-90 right triangle.
Angle at A is 60 degrees.  Angle at B is 30 degrees.  Angle at C is 90 degrees.


If c=18, then b=9.


Pythagorean Theorem:  {{{a^2+9^2=18^2}}}


{{{a=sqrt(18^2-9^2)}}}

{{{a=sqrt(243)}}}

{{{highlight(a=9sqrt(3))}}}