Question

The values of $cos(-{60}^o)$, $tan\left({150}^o\right)$ and $sin\left(240°\right)$ are

• A. $1/2,-1/\sqrt{3},-\sqrt{3}/2$
• B. $1/\sqrt{3},-1/\sqrt{3},-\sqrt{3}/2$
• C. $1/\sqrt{3},-1/\sqrt{3},-\sqrt{3}$
• D. $1/\sqrt{3},-2/\sqrt{3},-\sqrt{3}/2$

Answer 1

The correct option is A $1/2,-1/\sqrt{3},-\sqrt{3}/2$

$cos(-60)=cos60=1/2$
$tan150°=tan(180-30)=-tan30=-1/\sqrt{3}$
$sin240°=sin(270-30)=-cos30=-\sqrt{3}/2$