Write the set of values of a for which the equation √3 sin x − x cos x=a has no solution.
We have √3 sin x − x cos x=aThe LHS of this equation is of the form a sin x+b cos xWhere a=√3,b=−1∴r=√a2+b2=√3+1=2So that a=r cos αb=r sin α∴LHS=r cos α sin x+r sin α cos x=r [sin(x+α)]=2 sin(x+α)So,√3 sin x−cos x=a⇒2 sin(x+α)a⇒sin(x+α)=a2This equation has a solution only if −2 ≤ a≤2.∴The equation has no solution if a∈(−∞,−2)(2,∞).