Download 4.2 and 4.9 notes

Name _______________________________________ Date __________________ Class __________________
Geometry Section 4.2 Classifying Triangles
Classification
Description
Example
triangle that has three acute angles
triangle that has three congruent
acute angles
triangle that has one
right angle
triangle that has one obtuse angle
triangle with three congruent sides
triangle that has at least two
congruent sides
triangle that has no congruent
sides
Classify each triangle by its angle measures.
(Note: Some triangles may belong to
more than one class.)
1. ABD
________________________
2. ADC
________________________
3. BCD
________________________
Classify each triangle by its side lengths.
(Note: Some triangles may belong to more than one class.)
4. GIJ
________________________
5. HIJ
________________________
6. GHJ
________________________
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Holt McDougal Geometry
Name _______________________________________ Date __________________ Class __________________
Find the side lengths of each triangle.
7.
8.
9. Classify the triangle.
10. What type of triangle is
F isosceles acute
A acute, isosceles
G isosceles obtuse
B acute, scalene
H scalene acute
C obtuse, isosceles
J scalene obtuse
D obtuse, scalene
 ABC?
Decide if triangles are congruent by using the distance formula for diagonal sides.
Find the measure of each segment. Round answers to the nearest hundredth. Use the
information to determine if the triangles are congruent. Show all length calculations!!
RS = _______ RQ = _______ QS = ________
WY = ________ XY = ________ WX = ________
Are these triangles congruent to each other?_____ if yes, then RSQ  
Name _______________________________________ Date __________________ Class __________________
4.9 Isosceles and Equilateral Triangles
Theorem
Examples
Isosceles Triangle Theorem
If two sides of a triangle are congruent, then the
angles opposite the sides are congruent.
If RT  RS, then T  S.
Converse of Isosceles Triangle Theorem
If two angles of a triangle are congruent, then
the sides opposite those angles are congruent.
If N  M, then LN  LM.
Equilateral Triangle Corollary
If a triangle is equilateral, then it is equiangular.
(equilateral   equiangular )
Equiangular Triangle Corollary
If a triangle is equiangular, then it is equilateral.
(equiangular   equilateral )
If A  B  C, then AB  BC  CA .
Find each value.
1. mD  ________
2. GI  ________
3. mL  ________
4. RQ  ________
Name _______________________________________ Date __________________ Class __________________
5.
mU  ________
6. t  ________
7. What is the value of x in the figure?
8. What is the value of x in the figure?
9. What is the value of x in the figure?
10. What is the value of x in the figure?
11. What is the value of x?
x = _______
12. What is the value of x in the figure?