Answer:
m<D=50
Step-by-step explanation:
The reason is that ABOC is a quadrilateral, so its angle add up to 360*. Each of the tangent angles, <ABO and <ACO, has a measure of 90*.
m<ABO + m<ACO + m<A + m<O = 360
90 + 90 + m<A + m<O = 360
m<A + m<O = 180
80 + m<O =180
m<O = 100
If the measure of central angle <O is 100*, what is the measure of inscribed <D?
The measure of a central angle is equal to the measure of the arc it intercepts. If m<O = 100*, then m BC = 100.
The measure of an inscribed angle is half of the measure of the arc it intercepts. If m BC = 100*, then m<D = 50
m<D=50
