Answer
$\cos 18^{\circ}$ = 0.9510
Work Step by Step
Using calculator in degree mode-
$18$ → $\cos$ →→ 0.9510565163
i.e. $\cos 18^{\circ}$ = 0.9510565163
Rounding it to four places past the decimal point-
$\cos 18^{\circ}$ = 0.9510