https://www.khanacademy.org/math/geometry/hs-geo-congruence/xff63fac4:hs-geo-congruent-triangles/v/other-triangle-congruence-postulates 2021-07-02T09:35:28Z Triangle congruence postulates/criteria Sal introduces and justifies the SSS, SAS, ASA and AAS postulates for congruent triangles. He also shows that AAA is only good for similarity. For SSA, better to watch next video. Sal Khan video https://cdn.kastatic.org/googleusercontent/0eRO4OWRbVtbriGmo7x79sNd7U-XMRfk7oYDXtdz4Megakos8_IubqGv5NG1xm-jaYrBSJ2-ythdRqyimqwmZlY0iw Triangle congruence postulates/criteria Sal introduces and justifies the SSS, SAS, ASA and AAS postulates for congruent triangles. He also shows that AAA is only good for similarity. For SSA, better to watch next video. https://cdn.kastatic.org/ka-youtube-converted/8Ld8Csu4sEs.mp4/8Ld8Csu4sEs.mp4 808 Triangles https://www.khanacademy.org/math/geometry/hs-geo-congruence/hs-geo-congruence-theorems/v/congruent-legs-and-base-angles-of-isosceles-triangles 2021-02-16T16:08:13Z Proofs concerning isosceles triangles Sal proves that the base angles in isosceles triangles are congruent, and conversely, that triangles with congruent base angles are isosceles. He also proves that the perpendicular to the base of an isosceles triangle bisects it. Sal Khan video https://cdn.kastatic.org/googleusercontent/jEEfJHzFh50C2S_kmU9OCZKaxDbUeLZIoYZkeTy7-8xRyagY_ZkNjJ-ozLt80fhqzLRu8mhn-5yvYZKC43gfD3Xy Proofs concerning isosceles triangles Sal proves that the base angles in isosceles triangles are congruent, and conversely, that triangles with congruent base angles are isosceles. He also proves that the perpendicular to the base of an isosceles triangle bisects it. https://cdn.kastatic.org/ka-youtube-converted/7UISwx2Mr4c.mp4/7UISwx2Mr4c.mp4 543 Triangles https://www.khanacademy.org/math/geometry/hs-geo-congruence/hs-geo-congruence-theorems/v/equilateral-triangle-sides-and-angles-congruent 2021-02-16T16:08:14Z Proofs concerning equilateral triangles Sal proves that the angles of an equilateral triangle are all congruent (and therefore they all measure 60°), and conversely, that triangles with all congruent angles are equilateral. Sal Khan video https://cdn.kastatic.org/googleusercontent/QZ8jOQF11Eu-j3PcjFZSdaTq-lwCZ6mvoESc1Nv7ewc_iNlTMDB0BhS4Mzs2690ta8FsShYI4_IxL0-nJN-RywQJ Proofs concerning equilateral triangles Sal proves that the angles of an equilateral triangle are all congruent (and therefore they all measure 60°), and conversely, that triangles with all congruent angles are equilateral. https://cdn.kastatic.org/ka-youtube-converted/CYNUwiUzlPk.mp4/CYNUwiUzlPk.mp4 389 Triangles https://www.khanacademy.org/math/geometry/hs-geo-congruence/hs-geo-triangle-theorems/v/congruent-triangle-proof-example 2021-02-16T16:08:13Z Geometry proof problem: midpoint Sal proves that a point is the midpoint of a segment using triangle congruence. Sal Khan video https://cdn.kastatic.org/googleusercontent/s8sT_SliX29E4evlShM07KVeJtebkUpN6bzKCscjA_0GNtbGmbNIXp21TU8T0sc6KUQhrA1-HVMgkZ4gvuRD-a9q6Q Geometry proof problem: midpoint Sal proves that a point is the midpoint of a segment using triangle congruence. https://cdn.kastatic.org/ka-youtube-converted/RFesGHsuFZw.mp4/RFesGHsuFZw.mp4 346 Triangles https://www.khanacademy.org/math/geometry/hs-geo-congruence/hs-geo-triangle-theorems/v/congruent-triangle-example-2 2021-02-16T16:08:13Z Geometry proof problem: congruent segments Sal proves that two pairs of segments are congruent using the ASA and AAS congruence criteria. Sal Khan video https://cdn.kastatic.org/googleusercontent/gjBsNz5QritV7Wf3FQXHNRnmxMfPRtiBI7XXOwQnaAQvxpZ446bpEoJulwDk8o7CVV4BfF2RXZAcbwhEJVm-vj0 Geometry proof problem: congruent segments Sal proves that two pairs of segments are congruent using the ASA and AAS congruence criteria. https://cdn.kastatic.org/ka-youtube-converted/Xc3oHzKXVh8.mp4/Xc3oHzKXVh8.mp4 734 Triangles https://www.khanacademy.org/math/ka-revision-class-9-math/x4d0389c6e7b01cca:week-2/x4d0389c6e7b01cca:triangles/e/revision-triangles-ncert-for-up-math-class-9 2026-04-08T00:16:02.937952483Z Revision Triangles . Aakash Bagga exercise