Trigonometry

This chapter provides an overview of trigonometry, starting with the process of naming a right-angled triangle. It considers the simple trigonometric functions, looking at sine, cosine, and tangent. A sine is the ratio of the length of the opposite to the length of the hypotenuse, and a cosine is the ratio of the length of the adjacent to the length of the hypotenuse. Meanwhile, a tangent is the ratio of the length of the opposite to the length of the adjacent. The chapter then discusses radians, which are a way of subdividing angles within a circle; Pythagoras' theorem, which requires a right-angled triangle; and polar coordinates, which are especially useful when considering spherical or cylindrical spaces. It also examines the cosine rule and trigonometric identities.