### [Extension] Draw from triangle: draw normals from the incentre

Posted:

**Sat Sep 30, 2017 11:17 pm**I have a triangle ABC. I need to draw the three normals KO, LO, MO from the incentre O to sides of the triangle and then extend they outside of sides (blue lines on figure below). I know how to draw the incentre O (Extensions → Render → Draw from triangle → Incentre).

I have found the expressions for the segments AK = AM, BK = BL, CL = CM through the sides AB, AC, and BC:

AK=AM=(AB+AC-BC)/2,

BK=BL=(AB+BC-AC)/2,

CL=CM=(BC+AC-AB)/2.

Question. Could you please give me an idea how to calculate the positions K, M, and L?

Can I do this on the page Extensions → Render → Draw from triangle →Custom Points and Options with build-in expressions?

I have found the expressions for the segments AK = AM, BK = BL, CL = CM through the sides AB, AC, and BC:

AK=AM=(AB+AC-BC)/2,

BK=BL=(AB+BC-AC)/2,

CL=CM=(BC+AC-AB)/2.

Question. Could you please give me an idea how to calculate the positions K, M, and L?

Can I do this on the page Extensions → Render → Draw from triangle →Custom Points and Options with build-in expressions?