One of the diagnols of a rhombus is equal to its side so its largest angle is

 Let ABCD is a Rhombus, then AB=BC=CD = DA . and BD is a diagonal equal to side. Now, triangle ABD is a equilateral triangle so, all angle is 60° .

similarly triangle BCD is also a equilateral triangle so all angle 60° .

So, angle A=60° , angle C= 60° , angle B = 60+60= 120° and angle D= 60+60 = 12O°

after all smallest angle of Rhombus is 60° And largest angle is 120°