How to find the equation of a line with one point and no slope

the "y=mx+b" form (called the slope-intercept form of the equation of a line).

Explanation: Finding the equation for a line is a common problem in geometry and trigonometry. There are two common situations where you are asked to find the equation for a line: either you'll be provided with one point on the line and the slope of the line, or you'll be provided two points on the line.

The "b" value (called the y-intercept) is where the line crosses the y-axis.

So point (x1, y1) is actually at (0, b)  

and the equation becomes:

Start with

y − y1 = m(x − x1)

(x1, y1) is actually (0, b):

y − b = m(x − 0)

Which is:

y − b = mx

Put b on other side:

y = mx + b