Name: ___________________


kwizNET Subscribers, please login to turn off the Ads!
Email us to get an instant 20% discount on highly effective K-12 Math & English kwizNET Programs!

Grade 4 - Mathematics
4.2 Triangles

  • A triangle is a 3 sided polygon.
  • Triangles are two-dimensional figures.
  • Triangles can be classified according to the relative lengths of their sides as:
    • Equilateral triangle (3 sides of equal length)
    • Isosceles triangle (two sides are of equal length)
    • Scalene triangle (all sides have different lengths)
  • Triangles can also be classified according to the their internal angles as:
    • Right triangle (or right-angled triangle) has one 90 internal angle (a right angle). The side opposite to the right angle is the hypotenuse; it is the longest side in the right triangle. The other two sides are the legs of the triangle.
    • An obtuse triangle has one internal angle larger than 90 (an obtuse angle).
    • An acute triangle has internal angles that are all smaller than 90 (three acute angles).
    • An equilateral triangle is an acute triangle, but not all acute triangles are equilateral triangles.
    • An oblique triangle has only angles that are smaller or larger than 90. It is therefore any triangle that is not a right triangle.
  • The angles of a triangle add up to 180 degrees.
  • The sum of the lengths of any two sides of a triangle always exceeds the length of the third side. That is called the triangle inequality.
Example: A triangle with one obtuse angle and two sides equal.
Answer: Acute Isosceles triangle

Directions: Read the questions carefully and identify the type of triangle. Also draw an acute, obtuse, right, scalene, isosceles, equilateral triangle and show its properties.
Q 1: A polygon with 3 sides is called

Q 2: A right angle is
less than 90
Greater than 90
Equal to 90

Q 3: An obtuse angle is
Greater than 90
Equal to 90
Less than 90

Q 4: An acute angle is
Greater than 90
Less than 90
Equal to 90

Q 5: A figure that can be folded in half so that the 2 halves match is
a polygon

Q 6: I have an obtuse angle and 2 equal sides. What am I?
Obtuse Isosceles Triangle
Obtuse Equilateral Triangle
Right Scalene Triangle
Acute Isosceles Triangle

Q 7: I have 3 acute angles and 3 equal sides. What am I?
Obtuse Scalene Triangle
Acute Equilateral Triangle
Acute Scalene Triangle
Right Equilateral Triangle

Q 8: I have 3 acute angles and 2 sides the same length. What am I?
Acute Scalene Triangle
Acute Equilateral Triangle
Isosceles Acute Triangle
Obtuse Scalene Triangle

Question 9: This question is available to subscribers only!

Question 10: This question is available to subscribers only!

Subscription to kwizNET Learning System costs less than $1 per month & offers the following benefits:

  • Unrestricted access to grade appropriate lessons, quizzes, & printable worksheets
  • Instant scoring of online quizzes
  • Progress tracking and award certificates to keep your student motivated
  • Unlimited practice with auto-generated 'WIZ MATH' quizzes
  • Child-friendly website with no advertisements

© 2003-2007 kwizNET Learning System LLC. All rights reserved. This material may not be reproduced, displayed, modified or distributed without the express prior written permission of the copyright holder. For permission, contact
For unlimited printable worksheets & more, go to