This ques is very important and has been taken from the
Book- ML Aggarwal
Chapter- Trigonometric Identities
This ques has many sub questions.
Prove that following: (i) cos θ sin (90° – θ) + sin θ cos (90° – θ) = 1 (ii) tan θ/ tan (90o – θ) + sin (90o – θ)/ cos θ = sec2 θ (iii) (cos (90o – θ) cos θ)/ tan θ + cos2 (90o – θ) = 1 (iv) sin (90o – θ) cos (90o – θ) = tan θ/ (1 + tan2 θ)
Class10, ML Aggarwal, ques no 11, ICSE board