Cos(π-(2/5)x)+sin((3π/2)-(2/5)x)=0

Question

Cos(π-(2/5)x)+sin((3π/2)-(2/5)x)=0

Answer 1

Cos(π-(2/5)x)+sin((3π/2)-(2/5)x)=0
-Cos2/5 x -Cos2/5 x = 0
-2Cos2/5 x = 0
Cos2/5 x = 0
2/5 x = π/2 + πk , k ∈ Z
x = 5π/4 + 5πk/2 , k ∈Z