Find the trigonometric function of the form $$f(x)= a*\sin(x)+b*\cos(x)$$ that has a horizontal tangent at $$x=0$$ and satisfies $$f(0)=2$$. Which equation is correct?

For functions of the form $$f(x)= a*\sin(x)+b*\cos(x)$$,
f(0) = b and f’(0)= a.