(х-3) -(3х-4)=15
х-3-3х+4=15
-2х +1 =15
-2х= 15-1
-х= 14/2=7
х=-7
Проверим: (-7-3) -(3*(-7)-4)=15
-10-(-21-4)=15
-10+25 =15
15=15
<span>у=2х - в
4 = 2*3 - в
4 = 6 - в
в = 6 - 4 = 2
в = 2</span>
Sina=3/5
cos²a=1-9/25=16/25
cosa=4/5
tga=3/5 : 4/5 = 3/4
ctg=4/3