x-coordinate for specific point in a triangle

I'm trying to find a x-coordinate for the point (x,12) in triangle. The points of the are:

A = (0.2, 10)

B = (0.5, 10)

C = (0.2, 16)

The point (x,12) is on the BC-line. Can you help me?

Answer 1

[Roger Stafford]

This is an elementary analytic geometry problem. Write an expression for the slope of the line segment between B and C, and set it equal to the slope of the line segment between B and (x,12). Then solve this equation for the unknown x. Almost no matlab needed.

[Lily]

Ah thx... thoguht a function for this existed ;)

[the cyclist]

There are many ways to skin a cat, Lily. I agree with Roger that "almost no matlab" is needed. That being said, what you are asking for is a point along the linear interpolant of B and C, and there does exist a MATLAB function to do that:

interp1([10 16],[0.5 0.2],12)

gives the x value you want.

[Roger Stafford]

I agree with you, cyclist, but since you have a great many more points than I do in "Answers", I will greedily accept the credit here. I admittedly have a tendency to use mathematical non-matlab methods whenever they seem reasonably simple.

Answer 2

[the cyclist]

You can use the interp1() command to do this.