4+x/3=x/5 |*15
60+5x=3x
5x-3x=-60
2x=-60
x=-30
Решение
Sin (-11пи/4) = - sin[(12π/4) - π/4] = - sin(3π - π/4) = - sin(π/4) = - √2/2
<span>tg 17пи /6 = tg[(18</span>π/6) - π/6)] = tg(3π - π/6) = - tg(π/6) = - 1/√3
7x-2=3x+6
7x-2-3x-6=0
4x-8=0
x=2
1) = sinA*cosB-sinB*cosA+sinB*cosA= sinA*cosB
2) = 2cos^2A-cos^A- sin^2A = cos^2A-sin^2A=cos2A