Bài tập 2 trang 15 sgk Toán 11 tập 1 Cánh diều: Tính các giá trị lượng giác của mỗi góc sau: $225^{\circ}, -225^{\circ}, -1035^{\circ}, \frac{5\pi }{3}, \frac{19\pi }{2}, -\frac{159\pi }{4}$.
Bài Làm:
$sin\left ( 225^{\circ} \right ) = \frac{-\sqrt{2}}{2}, cos\left ( 225^{\circ} \right )=\frac{-\sqrt{2}}{2}, tan\left ( 225^{\circ} \right )=1, cot\left ( 225^{\circ} \right )=1$
$sin\left ( -225^{\circ} \right ) = \frac{\sqrt{2}}{2}, cos\left ( -225^{\circ} \right )=\frac{\sqrt{2}}{2}, tan\left ( 225^{\circ} \right )=-1, cot\left ( 225^{\circ} \right )=-1 $
$sin\left ( -1035^{\circ} \right ) = \frac{\sqrt{2}}{2}, cos\left ( -1035^{\circ} \right )=\frac{\sqrt{2}}{2}, tan\left ( -1035^{\circ} \right )=1, cot\left ( -1035^{\circ} \right )=1$
$sin\left ( \frac{5\pi }{3} \right ) = -\frac{\sqrt{3}}{2}, cos\left ( \frac{5\pi }{3}\right )=\frac{1}{2}, tan\left ( \frac{5\pi }{3} \right )=-\sqrt{3}, cot\left ( \frac{5\pi }{3} \right )=-\frac{\sqrt{3}}{3}$
$sin\left ( \frac{19\pi }{2} \right ) = -1, cos\left ( \frac{19\pi }{2}\right )=0, cot\left ( \frac{19\pi }{2} \right )=0 $
$sin\left ( -\frac{159\pi }{4}\right ) = -\frac{\sqrt{2}}{2}, cos\left ( -\frac{159\pi }{4}\right )=\frac{\sqrt{2}}{2}, tan\left ( -\frac{159\pi }{4} \right )=-1, cot\left ( -\frac{159\pi }{4} \right )=-1 $
