Gogeometry, Antonio Gutierrez, https://gogeometry.blogspot.com/2023/03/geometry-problem-1523-discover-how-to.html

 

Aops, Erik Lim, https://artofproblemsolving.com/community/c6t48f6h3821925_angle_aob_in_a_triangle_with_a_bisector_and_ratio_point

 

Fatih Eymen Hallac, https://www.facebook.com/photo?fbid=10163652155783190&set=gm.964231823089984&idorvanity=418649204314918

 

Romantics of Geometry, Nelson Tunala, repost of Confident Bee3824, in 'Trazos Auxiliares en Geometria', https://www.facebook.com/photo/?fbid=26405872469054547&set=gm.26727441590276194&idorvanity=1019808738132832

 

Gogeometry, Antonio Gutierrez, problem 920,

Gogeometry, Antonio Gutierez, https://gogeometry.com/school-college/6/p1582-outside-point-secants-circle-equal-angles-cyclic-quadrilateral-problem.html

 

Gogeometry, AntonioGutierez, https://gogeometry.com/school-college/6/p1591-quadrilateral-ABCD-congruent-sides-proportional-angles-7-10-5-calculate-angle-D.html