In this article, we present a comprehensive and updated synthesis of research on the knowledge of Mathematics teachers in initial training, both in general and in the areas of geometry and trigonometry. This synthesis is the result of a systematized bibliographic review that combines a secondary and tertiary study of the literature, including specific studies published between 1986 and mid-2020 in high-impact journals in the Americas and Europe, as well as previous reviews on this topic. Among the descriptive results, related to the characteristics of the research products considered, the limited research reported on the knowledge of teachers in initial training around trigonometry stands out. Also noteworthy is the predominance of internal studies—conducted by teachers or training institutions within their own courses or settings—originating from English-speaking countries, qualitative and empirical in nature, and on a small scale, typically involving between 1 and 50 participants. These characteristics regarding who, how, and where research in the field is conducted align with those reported in previous bibliographic reviews, showing that these trends have persisted for more than 15 years, regardless of the inclusion of Spanish- and Portuguese-speaking journals or the focus on specific educational levels and mathematical areas. Among the analytical results, concerning the content of the research products included in the review, the focus on mathematical knowledge of teachers in initial training stands out, in comparison to the attention given to teaching knowledge or in relation to the teaching practice. Likewise, there is a predominant prescriptive and deficit-oriented view of teacher knowledge, focusing on what teachers should know or what they do not do, do not know, or do not understand. In conclusion, we emphasize the need for more research on teacher knowledge in trigonometry, as well as large-scale studies conducted and published in Spanish- and Portuguese-speaking countries, with objectives that go beyond mathematical knowledge and the prescriptive and deficit-oriented view of the knowledge of teachers in initial training.En este artículo presentamos una síntesis –amplia y actualizada– de la investigación acerca del conocimiento del profesorado de Matemáticas en formación inicial, en general y en las áreas de geometría y trigonometría. Esta es fruto de una revisión bibliográfica sistematizada que aúna un estudio secundario y terciario de literatura. Como parte de los resultados destacamos el predominio de investigaciones empíricas, cualitativas, a pequeña escala y realizadas por instituciones/profesores formadores al interior de sus propios espacios/cursos, así como de estudios centrados en el conocimiento matemático del profesorado, llevados a cabo desde una perspectiva prescriptiva y deficitaria. Concluimos subrayando la necesidad de más investigaciones sobre el conocimiento del profesorado en el área de trigonometría, así como de estudios a gran escala, realizados y publicados en países hispano/lusohablantes, y con objetivos que trasciendan el foco en el conocimiento matemático y la visión prescriptiva y deficitaria del conocimiento del profesorado en formación inicial.