aops, Saudi Pre-Test 2011, https://artofproblemsolving.com/community/c6t48f6h2747302_bt__2pt_if_ltbat__lt_bcs__10o_in_40o70o70o_triangle

 

aops, https://artofproblemsolving.com/community/c6t48f6h2745721_ab__mnmn_if_ac__m_ad__n_in_regular_heptagon_abcdefg

 

Geometria Top, Rodrigo Santana Porto, https://www.facebook.com/photo/?fbid=10159887455088304&set=gm.1106716920098676

 

Training Geometry Olympiad (youtube) https://www.youtube.com/watch?v=QkLNGWAnZLM

 

Peru Geometrico, Yusuf Zemzem, https://www.facebook.com/photo?fbid=10220853728806088&set=gm.3318129314966605

 

aops, https://artofproblemsolving.com/community/c4t48f4h2735489_find_the_angle_oie

 Not a nice proof, but synthetical!

Trazo Geometrico Maldito, Geom Airt, https://www.facebook.com/photo/?fbid=447143579772477&set=gm.1061148854397205

 

aops https://artofproblemsolving.com/community/c4t48f4h2734068_prove_that_mi_is_perpendicular_to_bc

 

Tuymaada Junior 2006, https://artofproblemsolving.com/community/c6t48f6h1837994_equal_segments_wanted_starting_with_an_isosceles_and_right_triangle

 

aops, Catalin Bordea, https://artofproblemsolving.com/community/c6t48f6h2731831_suitable_proportion_for_trisecting_the_angle

 

Fake OMA Foros Open, 2017, https://artofproblemsolving.com/community/c6t48f6h2730928_ltbac__2ltabm_if_bc__cd__ac__bd

 

aops, https://artofproblemsolving.com/community/c4t48f4h2730157_calculating_the_angles_of_triangle_kem

 

Pedro Miranda, Training Geometry Olympiad, https://www.facebook.com/photo/?fbid=4533705923372103&set=gm.589447512315566