The Riemann zeta function(RZF), ζ(s), is a function of a complex variable s = x + iy, which is analytic for x > 1. The Dirichlet Eta Function(DEF), η(s), is also a function of a complex variable s, which is analytic for x > 0. The zeros of RZF and DEF are all same. The Riemann hypothesis(RH) states that the non-trivial zeros of RZF is of the form s = 0.5 + iy. The clue of our proof stems from the symmetry properties of RZF zeros, stating that if there exists a zero whose real part is not 0.5, such as ζ(α+ iβ) = 0,0 <α < 0.5, also ζ(1-α+ iβ)=0, called the critical line symmetry. Then, the two symmetric zeros should be on the two edge lines of a strip α ≤ �� ≤ 1−α. In the strip there are infinitely many lines that are parallel to the edge lines. Our question was, when that strip is mapped by DEF, will these parallel relationships be kept? If the parallel relationships are kept, RH is true, if not, RH may be false. So, we identified four possible graphic patterns that may satisfy the critical line symmetry. We found that DEF can’t satisfy any of the four patterns. So, RH is true.