Question

sinx*（-5/13）+cosx*12/13=3/5

Answer 1

y = arccos(5/13),

5/13 < 5/10 = 1/2,

0 < y < 60度.

0 < x < 90度 ,0 < y < 30度,

0 < x+y < 120度.

sinx(-siny) + cosx(cosy) = cos(x+y) = 3/5.

3/5 = 39/65 > 25/65 = 5/13.

360度-y < x+y < 360度.

x+y = 360度 - arccos(3/5),

x = 360度 - arccos(3/5) - arccos(5/13)