Question

Question 1 (iii)
Evaluate :
$cos{48}^{\circ }-sin{42}^{\circ }$

Answer 1

$cos{48}^{\circ }-sin{42}^{\circ }$
$=cos({90}^{\circ }-{42}^{\circ })-sin{42}^{\circ }$
$=sin{42}^{\circ }-sin{42}^{\circ }=0$ (As, cos (${90}^{\circ }$ - A) = sin A)