( cosec Φ-cotΦ)^2 = 1-cosΦ/ 1+cosΦ

Trigo

identitas

*

cosec x = 1/sin x

cot x  = cos x/sin x

sin² x + cos ² x = 1

*

(cosec x – cot x)² = (1- cos x)/ (1 + cos x)

ruaskiri  = ( cosec x – cot x)²

= { 1/sin x  - cos x/sin x)²

= { (1 – cos x)/ (sin x) }²

= (1 – cos x)² / (sin x)²

= (1 – cos x)²  / (1 – cos² x)

= (1 – cos x)(1 – cos x) / (1 – cos x )(1 + cos x)

= (1 – cos x)/(1 + cos x)