## Elementary Geometry for College Students (7th Edition)

This triangle is an isosceles triangle. Therefore the length of the opposite side equals to the length of the adjacent side, so $tan R =\frac{opposite}{adjacent}=1$
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 $tan R =\frac{opposite}{adjacent}=1$