A rhombus has sides 10 cm long and an angle of m<DAB=60°. Find the diagonals of the rhombus.
if you draw the diagonals
... you will see that they make four 30º-60º-90º right triangles
the hypotenuse is 10 , so the other sides are 5 and 5√3
... these sides are half the length of the diagonals