Page 167 - Mathematics_Form_Two

Trigonometry

Chapter Eight

Trigonometry
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Mathematics for Secondary Schools

Introduction

Accurate measurements such as distances, angles, and navigation would be difficult

without having the knowledge of trigonometry. In this chapter, you will learn
trigonometric ratios, trigonometric ratios of special angles, and perform calculations
that involve angles of elevation and depression. The competencies developed will enable

you to solve various problems related to building constructions, designing, navigation,
and many other applications.

Think
Imagine what would happen in a world without global positioning
systems and other navigation technologies.

Trigonometric ratios

Sine, cosine, and tangent are the basic
trigonometric ratios abbreviated as ‘sin’, their real life applications.
‘cos’, and ‘tan’. These are referred to as 2. On a sunny day, place a long stick
ratios because they are defined by ratios vertically on the ground, then
of the sides of a right-angled triangle. measure the height and length of its
Other trigonometric ratios derived from shadow.
these basic ratios are secant, cosecant, 3. Measure the shadow of a tall object
and cotangent. These are reciprocals of such as a tree or building and use
the three basic trigonometric ratios.
similar triangles to estimate its
height.
Activity 8�1: Measuring heights using
shadows 4. Share your findings with the
1. Explore the basic trigonometric class, explaining your process and
ratios (sine, cosine, and tangent) and justifying your results.

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