Answer:
∠R ≈ 46.4°
Step-by-step explanation:
Since the triangle is right we can use the tangent ratio to calculate ∠R
In relation to ∠R
TI is the side opposite
RT is the adjacent side and RI is the hypotenuse
tan R = [tex]\frac{opposite}{adjacent}[/tex] = [tex]\frac{21}{20}[/tex], hence
R = [tex]tan^{-1}[/tex]([tex]\frac{21}{20}[/tex]) ≈ 46.4°
