exact ratios

 sin60°cos30°-sin30°cos60°=sin30°

(sqrt(3)/2)(sqrt(3)/2) - (1/2)(1/2)  =  (1/2) 

(3/4)  - (1/4)  = (1/2)

Which is true.....

prove that

A) sin60°cos30°-sin30°cos60°=sin30°

$\sin{(60^{\circ})}\cdot \cos{(30^{\circ})} - \cos{(60^{\circ})}\cdot \sin{(30^{\circ})} = \sin{( 60^{\circ} - 30^{\circ} )} = \sin{( 30 ^{\circ} )}$