The source of the topic of this thesis is from the Courant Institute of Mathematics (Courant inst.), edited by the author Li Ta-Tsien (1998). The book that was written by Horn and Johnson (1985), the scholars used e^A to express Taylor’s expansion, in which A is a matrix, and that is, I+A+A^2/2!+A^3/3!+⋯. This book also applied Taylor’s expansion to extend the definition of trigonometric functions to matrices. The aim was to explore whether the trigonometric identities on real numbers were extended to matrices. Therefore, the focus of this thesis was to study the conditions for their establishment. If they were not established, examples would be used to illustrate how trigonometric identities did not meet the conditions for establishment. If they were established, evidence and concrete example would also be provided to verify them.