Q13 of 186 Page 350

sin (45° + θ) – cos (45° – θ) = ?

Consider sin (45° + θ) – cos (45° – θ) = sin (45° + θ) – sin (90° – (45° – θ))

= sin (45° + θ) – sin (45° + θ)

= 0

If A and B are acute angles such that sin A = cos B then (A + B) = ?

If cos (α + β) = 0 then sin (α – β) = ?

sec² 10° – cot² 80° = ?

cosec² 57° – tan² 33° = ?