А) cos(a)-cos(b)=-2sin( a+b/2)sin( a-b/2)
cos36°-cos24°=-2sin(36°+24°/2)sin(36°-24°/2)=
-2sin30°sin4°=-2*1/2*sin4°=-sin4°
6х-17=124-4х
6х+4х=124+17
10х=141
х=141÷11
х=14.1
1) tgx = 2
x = arctg2 + πn, n∈Z
2) tgx = 5
x = arctg5 + πk, k∈Z
-2,(7) -0,142536 0,125 0,1(25)
( √7 - √12)( √ 7 - 3√3)=(√7)^2- 3√21-√84+3√36=7-3√21 - √84+12=19-3√21 - 2√21=19-<span>√21</span>