Big Ideas Math Geometry, 2014
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Big Ideas Math Geometry, 2014 View details
2. Finding Arc Measures
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Exercise 14 Page 542

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: 315^(∘)

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. These 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.
A semicircle is an arc with endpoints that lie on a diameter. The measure of a semicircle is 180^(∘).
Now, let's consider the given diagram.
The arc that we are looking at is EBD. It is the longest arc that connects the endpoints E and D. Therefore, EBD 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. mEBD=360^(∘)-mED Looking at the diagram, we can see that mED=45^(∘).
mEBD=360^(∘)-mED
mEBD=360^(∘)- 45^(∘)
mEBD=315^(∘)