Question

Y=1/6cos²x-2sin²x+6sinxcosx+1 is equal to-

Answer 1

✍satyam _bradwaj

solution

Let,  y=10cos2x−6sinxcosx+2sin2x

⇒y=8cos2x+2(sin2x+cos2x)−6sinxcosx 

         =4(1+cos2x)+2−3sin2x=6+4cos2x−3sin2x

Hence the range of y is,

 −32+42+6≤y≤32+42+6⇒1≤y≤11