1. Check the picture atached.
2. R is the radius, so TRS is a central angle and its measure is 98°, so arc ST has measure 98° as well.
3. TUS is an inscribed angle intercepting arc ST, so the measure of TUS is 1/2 of the measure of arc ST = 49°
4. Remark we can also say directly that m(TUS)=1/2m(TRS) since they intercept the same arc.
