In an acute-angled triangle MNP, the bisector of angle M intersects the height NK at point O.
In an acute-angled triangle MNP, the bisector of angle M intersects the height NK at point O. Moreover, OK = 9cm. Find the distance from point O to line MN.
MS is the bisector of the angle M.
The distance from a point to a straight line is the perpendicular dropped from a point to a straight line. Let the height OH be the distance from point O to straight line MN.
Consider triangles MHO and MCO.
In the MTH triangle: angle ОМH = angle М / 2 (since MC is a bisector), angle МHО = 90 degrees (since OH is height).
Consider the MCO triangle: angle OMC = angle M / 2 (since MC is a bisector), angle MCO = 90 degrees (since OH is height).
The MO side is the common side of both triangles.
Consequently, the triangles MHO and MKO are equal in side and two adjacent angles.
Therefore, OH = OK = 9 cm.
Answer: OH = 9 cm.