Question

For \[t=\cos x\], what is \[dt\]?

Options

• \[dt=\sin x\,dx\]

• \[dt=\sec^2x\,dx\]

• \[dt=-\sin x\,dx\]

• \[dt=-\cos x\,dx\]

Answer 1

Differentiate \[t=\cos x\] with respect to \[x\]. Since the derivative of \[\cos x\] is \[-\sin x\], \[dt=-\sin x\,dx\].