A minor arc is an arc that measures less than 180^(∘). A major arc is an arc that measures greater than 180^(∘).
A semicircle is an arc with endpoints that lie on a diameter.
Type: Major arc Measure: 240^(∘)
Practice makes perfect
An arc is a portion of a circle defined by two endpoints. A central angle separates the circle into two arcs — the major arc and the minor arc. The measures of these arcs are related to the measure of the central angle.
Arc
Measure
A minor arc is the shortest arc connecting two endpoints on a circle.
The measure is less than 180^(∘) and is equal to the measure of its related central angle.
A major arc is the longest arc connecting two endpoints on a circle.
The measure is greater than 180^(∘) and is equal to 360^(∘) minus the measure of the minor arc with the same endpoints.
The arc that we are looking at is QRT. It is the longest arc that connects the endpoints Q and T. Therefore, QRT is a major arc. The measure of a major arc is equal to 360^(∘) minus the measure of the minor arc with the same endpoints.
mQRT=360^(∘)-mQT
Looking at the diagram, we can see that mQT=120^(∘).
