Select the Polygonal Lasso Tool (l) and create a triangular shape -holding down the Shift key whilst making the triangle will ensure each side is perfectly straight.
使用多边形套索工具(L)按住shift，创建一个三角形，以保证每条线都是直的。
2
By line one does not mean a straight line, or a circle or a triangle, but the.
所谓线条，并不是指一条直线，一个圆圈，或一个三角形，而是大自然的。
3
Let's say you're looking straight ahead at the surface of a triangle .