Warm Up Classify each angle as acute, obtuse, or right. 1. 2. 3.
19
Holt McDougal Geometry 4-1 Classifying Triangles Warm Up Classify each angle as acute, obtuse, or right. 1. 2. 3. 4. If the perimeter is 47, find x and the lengths of the three sides. right acute x = 5; 8; 16; 23 obtuse
description
Warm Up Classify each angle as acute, obtuse, or right. 1. 2. 3. 4. If the perimeter is 47, find x and the lengths of the three sides. right. acute. obtuse. x = 5; 8; 16; 23. Today’s Goals!. Classify triangles by their angle measures and side lengths. - PowerPoint PPT Presentation
Transcript of Warm Up Classify each angle as acute, obtuse, or right. 1. 2. 3.
Holt McDougal Geometry
4-1 Classifying Triangles
Warm UpClassify each angle as acute, obtuse, or right.
1. 2.
3.
4. If the perimeter is 47, find x and the lengths of the three sides.
right acute
x = 5; 8; 16; 23
obtuse
Holt McDougal Geometry
4-1 Classifying Triangles
Classify triangles by their angle measures and side lengths.
Use triangle classification to find angle measures and side lengths.
Today’s Goals!
Holt McDougal Geometry
4-1 Classifying Triangles
Recall:
Triangle - ( ) is a polygon with three sides.
Triangles can be classified in two ways:
by their angle measures
by their side lengths.
Holt McDougal Geometry
4-1 Classifying Triangles
B
AC
AB, BC, and AC are the sides of ABC.
A, B, C are the triangle's vertices.
Holt McDougal Geometry
4-1 Classifying Triangles
Acute Triangle
Three acute angles
Triangle Classification By Angle Measures
Holt McDougal Geometry
4-1 Classifying Triangles
Equiangular Triangle
Three congruent acute angles
Triangle Classification By Angle Measures
Holt McDougal Geometry
4-1 Classifying Triangles
Right Triangle
One right angle
Triangle Classification By Angle Measures
Holt McDougal Geometry
4-1 Classifying Triangles
Obtuse Triangle
One obtuse angle
Triangle Classification By Angle Measures
Holt McDougal Geometry
4-1 Classifying Triangles
Use the figure to classify each triangle by its angle measures.1.
DFG
2.
DEG
3.
EFG
Holt McDougal Geometry
4-1 Classifying Triangles
Equilateral Triangle
Three congruent sides
Triangle Classification By Side Lengths
Holt McDougal Geometry
4-1 Classifying Triangles
Isosceles Triangle
At least two congruent sides
Triangle Classification By Side Lengths
Holt McDougal Geometry
4-1 Classifying Triangles
Scalene Triangle
No congruent sides
Triangle Classification By Side Lengths
Holt McDougal Geometry
4-1 Classifying Triangles
Classify each triangle by its side lengths.
1. EGF
2. DEF
3. DFG
Holt McDougal Geometry
4-1 Classifying Triangles
Holt McDougal Geometry
4-1 Classifying Triangles
Remember!When you look at a figure, you cannot assume segments are congruent based on appearance. They must be marked as congruent.
Holt McDougal Geometry
4-1 Classifying Triangles
Find the side lengths of JKL.
Solve for x!
Step 1 Find the value of x.
JK = KL Notice Congruent Marks
4x – 10.7 = 2x + 6.3
2x = 17.0x = 8.5
Step 2 Substitute 8.5 into the expressions to find the side lengths.
JK = 23.3 KL = 23.3 JL = 44.5
Holt McDougal Geometry
4-1 Classifying Triangles
Find the side lengths of equilateral FGH.
FG = GH = FH
3y – 4 = 2y + 3
y = 7
FG = 17
FG = GH = FH = 17
Holt McDougal Geometry
4-1 Classifying Triangles
Quiz
Classify each triangle by its angles and sides.
1. MNQ
2. NQP
3. MNP
4. Find the side lengths of the triangle.
acute; equilateral
obtuse; scalene
acute; scalene
29; 29; 23
Holt McDougal Geometry
4-1 Classifying Triangles
Assignment
• P. 219 12-19,23-34
