Cторона меньшая x
тогда две другие по 3x
x+3x+3x=35
7x=35
x=5
5 15 15
3х+2*(х-1)=3
3х+2х-2=3
3х+2х=3+2
5х=5
х=5:5
х=1
Левая часть.
(3/(x+4))+(6x/(x^2+x-12))-(1/(x-3))=
(3(x-3)-(x+4))/((x+4)(x-3))+(6x/(x^2+x-12))=
(2x-13)/((x+4)(x-3))+(6x/((x+4)(x-3)))=
(8x-13)/((x+4)(x-3))=
(8x-13)/((x+4)(x-3)) * ((x-4)/(x-4))=
((8x-13)*(x-4))/((x^2-16)(x-3))
Поделим левую часть на правую.
[ ((8x-13)*(x-4))/((x^2-16)(x-3)) ] / ((8x-13)/(x^2-16))=
[ ((8x-13)*(x-4))/((x^2-16)(x-3)) ] * ((x^2-16)/(8x-13))=
(x-4)/(x-3)
1)cos²a+cos²a=2cos²a
2)cos²a+sin²a/tg²atg²a=1/1=1