(x+8)(x-12)=x²+8x-12x-96=x²-4x-96
D=b²-4ac, a=1,b=4,c=96
D=16+384=400
Ответ:
Tg(π/4+x)==(tgπ/4+tgx)/(1-tgπ/4*tgx)=(1+tgx)/(1-tgx)
AB=√(0-2)²+(1-1)²+(6-2)²=√(4+0+16)=√20
BC=√(2-0)²+(5-1)²+(6-6)²=√(4+16+0)=√20
CD=√(0-2)²+(5-5)²+(2-6)²=√(4+0+16)=√20
AD=√(0-2)²+(5-1)²+(2-2)²=√(4+16+0)=√20
AB=BC=CD=AD