Let 2 sin a + 3 cos b = 3 and 3 sin b + 2 cos a = 4 then
a+b=(4n+1)π2,nϵI
a and b can be two non right angles of a 3 - 4 - 5 triangle with b > a.
Squaring and adding
sin (a + b) = 1
a+b=(4n+1)π2,nϵIa+b=π2,b=π2−a⇒ 5 sin a=3 ⇒ cos a=45
sin b=45 and cos b=45
Hence b > a