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: 270^(∘)
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 PRT. It is the longer arc that connects the endpoints P and T. Therefore, PRT is a major arc.
To find its measure, we will need to use that we know that the minor arc, TP, has a measure of 90 and that the measures of the major and the minor arc add to 360.
m PRT+mTP=360
⇓
m PRT = 360 - mTP = 360 - 90 = 270
