锐角三角函数知识是建立在直角三角形上的,然而在许多求锐角三角函数的试题中,不见直角三角形,它需要我们见机行事,巧妙的构造出相应的直角三角形,才能迅速解决这类三角函数题。对于以正方形网格为背景的这类问题,则要注意利用格点连线的特殊位置 The knowledge of acute trigonometrical functions is based on right-angled triangles. However, in many test questions that seek trigonometric trigonometric functions, the right-angled triangles are not found. It requires us to look at the camera and skillfully construct the corresponding right-angled triangles in order to quickly solve such trigonometric functions . For the square grid in the background of such problems, we must pay attention to the use of grid connection special position