In this chapter, students will learn to define trigonometric ratios such as sine, cosine, tangent, cosecant, secant, and cotangent with respect to a right-angled triangle. The chapter explains how these ratios depend on the angles of the triangle and helps students understand their mathematical significance.

Students will also calculate trigonometric ratios of standard angles like 0°, 30°, 45°, 60°, and 90°, and learn the relationships between trigonometric ratios of complementary angles. This chapter builds a strong foundation for advanced trigonometry and is essential for solving real-life problems and board examination questions.