Answer:
∠ U = 12°
Explanation:
the inscribed angle RST is half the measure of its intercepted arc RT , then
arc RT = 2 × ∠ RST = 2 × 30° = 60°
the secant- tangent angle U is equal to half the difference of its intercepted arcs, that is
∠ U =
( RS - RT ) =
× (84 - 60)° =
× 24° = 12°