Question 956253
 an equilateral triangle has {{{15cm}}} on each side 
the height of the triangle 


{{{ drawing( 600, 600, -10, 20, -10, 20,triangle(0,0,15,0,7.5,12.99),line(7.5,0,7.5,12.99),
locate(1.5,7.5,15cm),locate(13.5,7.5,15cm),locate(7.7,7.5,h),locate(3.5,0.8,7.5cm),
graph( 600, 600, -10, 20, -10, 20,0)) }}}

use Pythagorean theorem to find {{{h}}}

{{{h^2=(15cm)^2-(7.5cm)^2}}}

{{{h^2=225cm^2-56.25cm^2}}}

{{{h^2=168.75cm^2}}}

{{{h=sqrt(168.75cm^2)}}}

{{{highlight(h=12.99cm)}}}