Ans: D
Let $r$ be the length of the hypotenuse.
Let $r$ be the length of the hypotenuse.
By Pythagorus Theorem, we have
$\begin{array}{rcl}
r^2 & = & 8^2 + 15^2 \\
r^2 & = & 289 \\
r & = & 17
\end{array}$
Hence, we have
$\begin{array}{rcl}
\cos \theta – \sin \theta & = & \dfrac{8}{17} – \dfrac{15}{17} \\
& = & \dfrac{-7}{17}
\end{array}$
