1y= \cos x+\sin x 2/ y=\cos \frac{x+1}{x+2} 3/ y=\cos \sqrt{x^{2}-3x+2} 4/y=\sin \sqrt{x+4} 5/y=\frac{2}{\cos 2x} 6/y=\sin \frac{2x}{x-2} 7/ y=\frac{1}{\sin x}-\frac{1}{2\cos x} 8/ y=\frac{1}{2\cos x-1} 9/y=\cos \frac{1}{x^{2}-1}