Answer:
cos (270° - θ) = -sinθ
Step-by-step explanation:
Explanation:-
Trigonometry sum or difference formula
Cos (A+B) = cos A cos B - sin A sin B
Cos (A+B) = cos A cos B + sin A sin B
Given cos (270° - θ) = cos 270° cosθ + sin 270° sinθ
Cos 270° = cos (180°+90°) = -cos 90° = 0
sin 270° = sin (180°+90°) = -sin 90° = -1
now
cos (270° - θ) = cos 270° cosθ + sin 270° sinθ
cos (270° - θ) = (0) cosθ + (-1) sinθ = -sinθ
Final answer:-
cos (270° - θ) = -sinθ
