Lesson1. Trigonometric ratios (घर के लिए ट्यूशन रांची )

What is Trigonometry? 

 Ans: It is that Branch of mathematics which deals with the measurement of angles and the problems allied with angles. 

Which are the six trigonometric ratios? 

Ans : sin, cos, tan, cosec, sec, cot

Let angle A be an acute angle of  of a right angled triangle  ∆ABC.

Then 

Sin A = perpendicular/hypotenuse

Cos A = base / hypotenuse

Tan A = perpendicular / base

Cosec A = hypotenuse/perpendicular

Sec A = hypotenuse/base

Cot A = base/perpendicular

How to remember these formulae? 

Remember the sentence :

" Some People Have Curly Brown Hair Tightly Pulled Back "

Some=People/Have

Curly=Brown/Hair

Tightly=Pulled/Back

sin A= p/h, 

cos A= b/h, 

tan A= p/b

RECIPROCAL OF MAIN FORMULAE

COSEC  A=H/P 
SEC A=H/B 
COT A= B/P 

Reciprocal relation

cosec A = 1/ sin A

sec A = 1/ cos A

cot A = 1/ tan A