Minor Arc Fabbc4
1. Problem statement:
In the figure, \overline{AD} and \overline{CE} are diameters of circle $P$.
The central angle $\angle CPB$ measures $38^\circ$.
The central angle $\angle DPE$ measures $93^\circ$.
Find the measure of the minor arc $\widehat{AB}$.
2. Formula and important rules:
A central angle has measure equal to the measure of its intercepted arc.
Therefore $m(\widehat{CB})=m(\angle CPB)=38^\circ$.
When two points are endpoints of a diameter they are opposite on the circle, so their direction angles differ by $180^\circ$.
3. Intermediate work and reasoning:
Because $A$ and $D$ are opposite and $C$ and $E$ are opposite, the central angle between $A$ and $C$ equals the central angle between $D$ and $E$.
Hence $$m(\widehat{AC})=m(\angle DPE)=93^\circ$$.
Arc $AC$ is composed of arcs $AB$ and $BC$.
So $$m(\widehat{AC})=m(\widehat{AB})+m(\widehat{BC})$$.
4. Solve for the desired arc:
Rearrange to get $$m(\widehat{AB})=m(\widehat{AC})-m(\widehat{CB})$$.
Substitute the known values.
$$m(\widehat{AB})=93^\circ-38^\circ$$
Simplify.
$$m(\widehat{AB})=55^\circ$$
5. Final answer:
The measure of minor arc $\widehat{AB}$ is $55^\circ$.