Trigonometry

• Right angle triangle (Revision)
• Relationship between right angle triangles and trigonometric ratios.
• Sine, cosine and tangent of acute angles using tables.
• Applications of trigonometric ratios to finding distances and lengths.

Right Angled Triangle

A right angled triangle has one of its angles equal to 90^O. That is, if a triangle has one of its three angles equal to 90^O then it is a right angled triangle. A little square at the corner (angle) signifies that the angle is 90^O.

Right Angled Triangle and the Trigonometric Ratios

A trigonometric ratio is a ratio of the lengths of any two sides of a right – angled triangle. The longest side is called the Hypotenuse, the side facing the required angle is called the opposite and the last side is called the adjacent.

= 16.384 cm

= 16 cm to 2 s.f.

Example

1. Calculate the value of y in the figure below.