Найдите значение выражения sqrt(72)cos^2(13Pi/8)-sqrt(18)
cos^2(13π/8)=(1+cos(26π/8))/2=(1+cos(24π+2π)/8)/2= =(1+cos(3π+(π/4)))/2=(1-cos(π/4))/2=(1-(sqrt(2))/2)/2= =(1/2)-(sqrt(2))/4; sqrt(72)*cos^2(13π/8)–√18=(sqrt(72))/2-(sqrt(144))/4- sqrt(18)= =3sqrt(2)-3-3sqrt(2)=-3 О т в е т. -3