Explore Basics of Trigonometry And Trigonometric Ratios

Introduction

Basics of trigonometry is about learning the core three ratios sine, cosine and tangent. How are these ratios related to the three sides and the angles of a right angled triangle?

In the basics of trigonometry the reciprocals of ratios cosecant, secant and cotangent are also learnt. Each ratio and its reciprocal has its own specific formula which involves two sides and one relevant angle.

The trigonometric ratios formulas can be memorised to solve basic problems of trigonometry using the mnemonics "SPH - CBH - TPB". The trigonometric ratios of specific angle values of a right angled triangle can also be memorised.

There are following six trigonometric identities of complimentary angles that can be remembered to solve problems:

1. sin (90 - θ) = cos θ
2. cos (90 - θ) = sin θ
3. sec (90 - θ) = cosec θ
4. cosec (90 - θ) = sec θ
5. tan (90 - θ) = cot θ
6. cot (90 - θ) = tan θ

These mnemonics and identities further help in calculating the unknown angle and length perpendicular, base and hypotenuse of a right angled triangle.