Mathematics SSS 1 Third Term

WEEK 5

Trigonometry (I)       

Performance Objectives

Students should be able to;

1. Identify ratios forming cosine and tangent of marked angle
2. Draw right angle triangles
3. Use right-angle triangles to solve problems involving calculations of lengths

Basic Trigonometric Ratios (Sine, Cosine, Tangent, with respect to right-angled triangles)

Content

These trigonometric ratios are applicable to the right-angled triangle. A right-angle triangle is 90⁰. Thus the remaining two angles add up to 90⁰ since every triangle contains two right angles.

In ∆ABC, B + C = 90⁰.

Such angles whose sum is 90⁰ are said to be complementary angles. While capital letters are used for angles, small (lower case) letters are used for sides. Notice that the side opposite A is labelled a, the one opposite B is labelled b etc.