Question

can someone help me solve -10cosx-3sinx+9=0?

Answer 1

Do you want to verify this equation or
simplify?? Please clarify it.

Answer 2

10cos x+3 sinx =9
let 10=rsin a
3=r cos a
r sin(a+x)=9
a+x=sin^{-1}(9/r)
x=sin^{-1}(9/r)-a
r=sqrt(109) and a= tan^{-1}(10/3)