Sin22,5°sin22,5-cos22,5cos22,5 помогите пж 20 баллов

Question

Sin22,5°sin22,5-cos22,5cos22,5
помогите пж 20 баллов

Answer 1

Sin²α-cos²α=-(cos²α-sin²α)=-cos2α

sin22,5° *sin22,5°-cos22,5° *cos22,5°=-(cos²22,5°-sin²22,5°)=-cos(2*22,5°)=
=-cos45°=-√2/2

Comments

сепас