Triangle Worksheet Lesson 1

A triangle is a polygon with three sides and three angles. The sum of the three angles is 180 degrees

 Types of triangles   An equilateral triangle has three equal sides and three equal angles.   An isosceles triangle has two equal sides and two equal angles.   A scalene triangle has no equal sides and no equal angles.   An obtuse triangles has one angle greater than 90 degrees.   A right triangle has one 90 degree angle (a right angle).   An acute triangle has three angles that are each less than 90 degrees.

# Are the triangles acute, obtuse, or right?

Solution                    Measure all the sides and all the angles

Step 1:

Solution                    We can see that no two sides are equal and there is one acute angle

Step 2:                        Thus, the triangle is a, acute scalene triangle

Solution                    The answer is:   Acute scalene triangle

Step 3:

Complete

Try two practice problems:

# Are the triangles equilateral, isosceles, or scalene?

Are the triangles acute, obtuse, or right?

 A. B.

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