Introduction to Trignometry – Notes

Trigonometric Ratios and Angles

Trigonometry is the study of relationship between the angles and sides of triangles.

The ratios between the lengths of the sides of a right-angled triangle are relation with its acute angles is called trigonometric ratios.

N a right-angled triangle ABC, if ÐA is an acute angle:

• Sin ÐA 
• Cos
• Tan ÐA 
• Cosec ÐA 
• Sec ÐA 
• Cot ÐA 

If we know the value of any one of the trigonometric ratios of an acute angle in a right-angled triangle, we can calculate other trigonometric ratios of the angle.