The four sides and one diagonal of a rhombus each have sides 3√6 cm long. Find the area of the rhombus, in cm^2.
Since one of its diagonals is equal to its sides, then 2 EQUILATERAL triangles will emerge, to form the rhombus
Each angle of each equilateral triangle = = 60o
Area of any NON-RIGHT triangle = the PRODUCT of 2 of its CONSECUTIVE sides, TIMES the sine of the INCLUDED angle
So, AREA of one of this rhombus' 2 equilateral triangles = =
--- Substituting for sin 60o
As there are 2 of these equilateral triangles, AREA of both equilateral triangles/RHOMBUS = = =