# 5.7: Chapter 5 Review

Created by: CK-12

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**Keywords, Theorems and Postulates**

- Midsegment
- A line segment that connects two midpoints of adjacent sides of a triangle.

- Midsegment Theorem
- The midsegment of a triangle is half the length of the side it is parallel to.

- Perpendicular Bisector Theorem
- If a point is on the perpendicular bisector of a segment, then it is equidistant from the endpoints of the segment.

- Perpendicular Bisector Theorem Converse
- If a point is equidistant from the endpoints of a segment, then the point is on the perpendicular bisector of the segment.

- Point of Concurrency
- When three or more lines intersect at the same point.

- Circumcenter
- The point of concurrency for the perpendicular bisectors of the sides of a triangle.

- Concurrency of Perpendicular Bisectors Theorem
- The perpendicular bisectors of the sides of a triangle intersect in a point that is equidistant from the vertices.

- Angle Bisector Theorem
- If a point is on the bisector of an angle, then the point is equidistant from the sides of the angle.

- Angle Bisector Theorem Converse
- If a point is in the interior of an angle and equidistant from the sides, then it lies on the bisector of the angle.

- Incenter
- The point of concurrency for the angle bisectors of a triangle.

- Concurrency of Angle Bisectors Theorem
- The angle bisectors of a triangle intersect in a point that is equidistant from the three sides of the triangle.

- Median
- The line segment that joins a vertex and the midpoint of the opposite side (of a triangle).

- Centroid
- The point of concurrency for the medians of a triangle.

- Concurrency of Medians Theorem
- The medians of a triangle intersect in a point that is two-thirds of the distance from the vertices to the midpoint of the opposite side.

- Altitude
- A line segment from a vertex and perpendicular to the opposite side.

- Orthocenter
- The point of concurrency for the altitudes of triangle.

- Theorem 5-9
- If one side of a triangle is longer than another side, then the angle opposite the longer side will be larger than the angle opposite the shorter side.

- Converse of Theorem 5-9
- If one angle in a triangle is larger than another angle in a triangle, then the side opposite the larger angle will be longer than the side opposite the smaller angle.

- Triangle Inequality Theorem
- The sum of the lengths of any two sides of a triangle must be greater than the length of the third.

- SAS Inequality Theorem
- If two sides of a triangle are congruent to two sides of another triangle, but the included angle of one triangle has greater measure than the included angle of the other triangle, then the third side of the first triangle is longer than the third side of the second triangle.

- SSS Inequality Theorem
- If two sides of a triangle are congruent to two sides of another triangle, but the third side of the first triangle is longer than the third side of the second triangle, then the included angle of the first triangle is greater in measure than the included angle of the second triangle.

- Indirect Proof
- When the conclusion from a hypothesis is assumed false (or opposite of what it states) and then a contradiction is reached from the given or deduced statements.

## Review

If and are the midpoints of the sides they lie on, find:

- The perpendicular bisector of .
- The median of .
- The angle bisector of .
- A midsegment.
- An altitude.
- Trace onto a piece of paper with the perpendicular bisector. Construct another perpendicular bisector. What is the point of concurrency called? Use this information to draw the appropriate circle.
- Trace onto a piece of paper with the angle bisector. Construct another angle bisector. What is the point of concurrency called? Use this information to draw the appropriate circle.
- Trace onto a piece of paper with the median. Construct another median. What is the point of concurrency called? What are its properties?
- Trace onto a piece of paper with the altitude. Construct another altitude. What is the point of concurrency called? Which points of concurrency can lie outside a triangle?
- A triangle has sides with length and . Find the range of the third side.

## Texas Instruments Resources

*In the CK-12 Texas Instruments Geometry FlexBook, there are graphing calculator activities designed to supplement the objectives for some of the lessons in this chapter. See http://www.ck12.org/flexr/chapter/9690.*

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altitudes
angle bisector
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CK.MAT.ENG.SE.1.Geometry-Basic.5
CK.MAT.ENG.SE.2.Geometry.5
concurrency
indirect proof
inscribe
medians
mid-segment
Midsegment Theorem
midsegments
perpendicular bisector
perpendicular bisectors
proof
Segments
sides of triangles
triangle inequalities
Triangle Inequality Theorem
triangles

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## Date Created:

Feb 22, 2012## Last Modified:

Aug 21, 2014
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