MathDB

Geometry in a 45-60-75 triangle

Source:

May 18, 2015

geometry

Problem Statement

From the foot

D

of the height

CD

in the triangle

ABC,

perpendiculars to

BC

and

AC

are drawn, which they intersect at points

M

and

N.

Let

\angle CAB = 60^{\circ} , \angle CBA = 45^{\circ} ,

and

H

be the orthocentre of

MNC.

If

O

is the midpoint of

CD,

find

\angle COH.

Back to Problems View on AoPS