Asquare is cut into two congruent triangles by drawing the diagonal between two corners. if the area of each triangle is 162 cm, what is the length of the side of the square?

Ok so area=162
since the triangles sides were cut out of a square, base=height
area=1/2bh=162
b=h
area=1/2b^2=162
times 2 both sides
b^2=324
sqrt both sides
b=18=h
the legnth of one side is 18cm
see diagram

another way, is total aera of square=areas of  both triangles=162+162=324
remember area of square=side^2 so
324=side^2
sqrt both sides
18=side

answer is 18cm