Question

if the perimeter of a equilateral triangle is 18cm then construct the triangle ​

Answer 1

perimeter is 18 so the side is 6cm .

now draw a segment of length 6cm then take a measure of 6 cm on bisector . keep it at one end and draw arc similarly do it from other pont and then join the end poinys with the intersection point of two arcs.

hope it will help you

Answer 2

We have to construct an equilateral triangle so all sides would be equal so if perimeter is 18cm so each side would be of 18/3=6cm.
Do first draw a line segment AB=6cm. We know that all angles of an equilateral triangle are of 60 degree so draw angles of 60 degree by taking A and B as centre uncommon ray both of the angles would be intersecting each​ other at a point name it as C .Your ABC triangle is ready!!