Reteach and Skills Practice Workbook

10–7
Name
Reteach
Triangles
Date
You can classify a triangle by the lengths of its sides or the
measures of its angles.
An equilateral triangle has three sides of equal length.
An isosceles triangle has at least two sides of equal length.
A scalene triangle has no sides of equal length.
4MG3.7
by length of sides
Chapter Resources
An acute triangle has three acute angles (less than 90°).
An obtuse triangle has one obtuse angle (greater than 90°
and less than 180°).
by measure of angles
A right triangle has one right angle (exactly 90°).
Classify each triangle. Use isosceles, equilateral, or scalene and
acute, right, or obtuse.
1.
2.
Copyright © Macmillan/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
5 yd
9 ft 9 ft
3 yd
9 ft
4 yd
3. 4 cm
12 cm
10 cm
4. Identify the term that does not belong with the other three.
A. right B. obtuse C. scalene D. acute
5. What kind of triangle has three sides of equal length?
F. equilateral G. scalene H. right J. acute
4.
5.
6. How many degrees does a straight line measure?
Grade 4 189 Chapter 10