minus angle การใช้

• P is a point inside triangle ABC, and D and E are the incenters of triangles APB and APC, and angle APB minus angle ACB is equal to angle APC minus angle ABC . Show that lines AP, BD and CE meet at a point.
• P is a point inside triangle ABC, and D and E are the incenters of triangles APB and APC, and angle APB minus angle ACB is equal to angle APC minus angle ABC . Show that lines AP, BD and CE meet at a point.