Answer
This triangle is an isosceles triangle.
Therefore the length of the opposite side equals to the length of the adjacent side, so $tan R =\frac{opposite}{adjacent}=1$
Work Step by Step
By definition, the tangent ratio is $tan R =\frac{opposite}{adjacent}$.
Here, this triangle is an isosceles triangle, as both angle $m\angle R = m \angle S = 45^{\circ} $.
Therefore the length of the opposite side equals to the length of the adjacent side, so $tan R =\frac{opposite}{adjacent}=1$
