问题描述
给定起点、直线长度和直线角度(相对于 x 轴)，我如何找到直线方程或绘制直线?
How can I find equation of a line or draw a line, given a starting point, length of line and angle of line (relative to x-axis)?
推荐答案
直线方程是这样的:
m*x + n = y
m可以通过角度计算；m = tan(角度)如果你知道一个起点，那么你就可以找到 n.
m can be calculated by angle; m = tan(angle)And if you know a start point then you can find n.
tan(angle) * startPoint_X + n = startPoint_Y
所以 n = startPoint_Y - (tan ( 角度) * startPoint_X )
如果你想画一条线段，知道长度、起点和角度，就会有两个方程.
If you want to draw a line-segment and you know the length, the start point and the angle, there will be two equations.
第一个是m*x + n = y(我们解决了).
The first is m*x + n = y (we solved it).
这意味着 m*(endPoint_X) + n = endPoint_Y
第二个是找到endPoint.
The second is to find the endPoint.
length^2 = (endPoint_X - startPoint_X)^2 + (endPoint_Y - startPoint_Y)^2
只有两件事我们还不知道:endPoint_x &端点_Y如果我们改写方程:
There are only two things that still we don't know: endPoint_x & endPoint_YIf we rewrite the equation:
length^2 = (endPoint_X - startPoint_X)^2 + ( m*(endPoint_X) + n - startPoint_Y)^2
现在我们知道除了 endPoint_X 之外的一切.这个方程将为我们提供 endPoint_X 的两个解.然后就可以找到两个不同的ednPoint_Y了.
now we know everything except endPoint_X.This equation will give us two solutions for endPoint_X.Then you can find two different ednPoint_Y.
这篇关于带角度的线方程的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！