用一副三角板，可以画出15,30,45,60,75,90,105,120,135,150,165°∴可以画出5个锐角，5个钝角
15,30,45,60,75,是锐角105,120,135,150,165°是钝角
是15,30,45,60,75,90,105,120,135,150,165度角
