sin\alpha > 0)\\sin\alpha = \sqrt{1-cos^2\alpha} = \sqrt{1-\frac49} = \frac{\sqrt5}3\\tg\alpha = \frac{sin\alpha}{cos\alpha} = \frac{\sqrt5}3*\frac32 = \frac{\sqrt5}2\\ctg\alpha = \frac1{tg\alpha} = \frac2{\sqrt5} = \frac{2\sqrt5}5" alt="cos\alpha = \frac23; 0 < \alpha < \frac\pi2 (=> sin\alpha > 0)\\sin\alpha = \sqrt{1-cos^2\alpha} = \sqrt{1-\frac49} = \frac{\sqrt5}3\\tg\alpha = \frac{sin\alpha}{cos\alpha} = \frac{\sqrt5}3*\frac32 = \frac{\sqrt5}2\\ctg\alpha = \frac1{tg\alpha} = \frac2{\sqrt5} = \frac{2\sqrt5}5" align="absmiddle" class="latex-formula">