This book is an introductory textbook for the trigonometry course for first-semester students in the mathematics education program. This book consists of two main chapters, the first chapter covers trigonometric functions and the second chapter covers trigonometric analysis. In the first chapter, it consists of several subsections such as angles, degrees, and triangles; ratios in right triangles; applications in right triangles; trigonometric functions in the Cartesian plane; trigonometric functions for acute angles; radian measure and its application; trigonometric functions in the circle; graphs of sine and cosine functions; and graphs of other trigonometric functions. Meanwhile, the second chapter contains basic trigonometric identities; verification of trigonometric identities; sum and difference identities; double angle identities; half angle identities; product to sum and sum to product identities, inverse trigonometric functions, and trigonometric equations.