Объяснение:
-36cos2a= -36(1-2sin²a)= -36(1-2*(√7/6)²)= -36*(1-2*7/36)= -36*(1-14/36)= -36*(-22/36)= 22
-cos7b/2sin14b= -cos7b/4sin7b*cos7b= -1/4sin7b= -1/4*0,1= -2,5
