Use phasors to simplify each of the following expressions into a single term [Hint: See Problem 7.26]: (a) v1​(t)=12cos(6t+30∘)−6cos(6t−45∘)V *(b) v2​(t)=−3sin(1000t−15∘)−6sin(1000t+15∘) +12cos(1000t−60∘)V