Answer:
Measure of arc TSU = 201°
Step-by-step explanation:
For the inscribed circle of triangle XYZ, we have;
∠XZY = 21°
Segment TZ and segment UZ are tangent to circle R
Therefore, ∠ZUR = ∠ZTR = 90° (angle formed by a tangent)
Length UR = Length TR = Radius of circle R
∴ ΔZTR ≅ ΔZUR Side Angle Side (SAS) rule of Congruency
∴ ∠RZT ≅ ∠RZU, (Congruent Parts of Congruent Triangles are Congruent, CPCTC)
∠XZY = ∠RZT + ∠RZU (Angle summation)
21° = ∠RZT + ∠RZU = 2×∠RZU (Transitive property)
∠RZU = 21°/2 = 10.5° = ∠RZT
∴ ∠URZ = 180- 90 - 10.5 = 79.5° = ∠TRZ (CPCTC)
arc TU = ∠URT = ∠URZ + ∠TRZ = 79.5 + 79.5 = 159° (angle addition)
∴ Measure of arc TSU = 360° - 159° = 201° (Sum of angles at the center of the circle R)
Measure of arc TSU = 201°.
