A)t = 9^sinx
t+ 1/t = 10/3
3t² + 3 = 10t
3t² - 10t +3 = 0
D = b²-4ac = 100-36=64
√D = 8
t₁ = 3 t₂=1/3
9^sinx=3 9^sinx=1/3
sinx = 1/2 sinx = -1/2
x =П/6+2Пn,n∈z x =-П/6+2Пm,m∈z
или x = 5П/6+2Пk, k∈z или x = -5П/6+2Пl, l∈z
Ответ: а) П/6+2Пn,n∈z; 5П/6+2Пk, k∈z; =-П/6+2Пm,m∈z; -5П/6+2Пl, l∈z
б) -19П/6; -17П/6; -13П/6