Вычеслить 1)cos 765* 2)sin (19/6)умножить на пи

1)cosa-cosb / cosa+cosb =  (-2sin((a-b)/2)*sin((a+b)/2)) / (2cos((a-b)/2)*cos((a+b)/2)) = -tg((a-b)/2)*tgn((a+b)/2) 2)sina+sinb / sina-sinb =    (2sin((a+b)/2)*cos((a-b)/2)) / (2sin((a-b)/2)*cos((a+b)/2)) = tg((a+b)/2)*ctg((a-b)/2) 3)sin2x+sin6x / cos2x-cos6x =  (2sin((2x+6x)/2)*cos((2x-6x)/2)) / (-2sin((2x-6x)/2)*sin((2x+6x)/2)) = -(sin4x*cos(-2x)) /(sin(-2x)*sin4x)= -ctg(-2x) = ctg2x 4) cosa-cosb / sina+sinb =  (-2sin((a-b)/2)*sin((a+b)/2)) / (2sin((a+b)/2)*cos((a-b)/2)) = -tg((a-b)/2) 5)  cos5x-cosx / sin5x+sinx =    (-2sin((5x-x)/2)*sin((5x+x)/2)) / (2sin((5x+x)/2)*cos((5x-x)/2)) = - (sin2x*sin3x) / (sin3x*cos2x) = -tg2x 6)cos2x-cos3x / sin2x+sin3x =  (-2sin((2x-3x)/2)*sin((2x+3x)/2)) / (2sin((2x+3x)/2)*cos((2x-3x)/2)) = -(sin(-1x/2)*sin(5x/2)) / (sin(5x/2)*cos(-1x/2)) = - tg(-x/2)

1)6sinx/2cosx/2+5cos²x/2-5sin²x/2+3cos²x/2+3sin²x/2=0 -2sin²x/2+6sinx/2cosx/2+8cos²x/2=0 sin²x/2-3sinx/2cosx/2-4cos²x/2=0  /cos²x/2≠0 tg²x/2-3tgx/2-4=0 tgx/2=a a²-3a-4=0⇒a1+a2=3 u a1*a2=-4⇒ a1=4⇒tgx/2=4⇒x/2=arctg4+πn⇒x=2arctg4+2πn a2=-1⇒tgx/2=-1⇒x/2=-π/4+ππn⇒x=-π/2+2πn 2)6√3sinx/2cosx/2-5cos²x/2+5sin²x/2-7cos²x/2-7sin²x/2=0 -2sin²x/2+6√3sinx/2cosx/2-12cos²x/2=0 sin²x/2-3√3sinx/2cosx/2+6cos²x/2=0  /cos²x/2≠0 tg²x/2-3√3tgx/2+6=0 tgx/2=a a²-3√3a+6=0 d=27-24=3 a1=(3√3-√3)/2=√3⇒tgx/2=√3⇒x/2=π/3+πn⇒x=2π/3+2πn a2=(3√3+√3)/2=2√3⇒tgx/2=2√3⇒x/2=arctg2√3+πn⇒x=2arctg2√3+2πn