Question

pls answer this question.... it's urgent...

Answer 1

hope it may help you.

Answer 2

$\sqrt{(0 - sina \alpha )2 + (0 - cosa \alpha )2}$
$\sqrt{a2cos2 \alpha +asin \alpha }$
$a \sqrt{cos2 \alpha + sin2 \alpha }$
a×1=a
Proved.