Cos^4 15pi/12-sin^4 5pi/12 Срочно)

Сos^4(5π/4)-sin^4(5π/12)=cos^4(π+π/4)-sin^4(π/2-π/12)= =cos^4(π/4)-cos^4(π/12)=(1/√2)^4-(1+cos(π/6))²/4= =1/4-(1+√3/2)²/4=1/4*(1-(1-√3/2)²)=1/4(1-1+√3-3/4)= =1/4*(√3+3/4)=√3/4-3/16