Types of Triangles Practice Problems and Worksheets

Master triangle classification with interactive practice problems. Learn equilateral, isosceles, scalene, right, acute, and obtuse triangles through step-by-step solutions.

📚What You'll Master in Triangle Types Practice
  • Identify and classify triangles by side lengths: equilateral, isosceles, and scalene
  • Distinguish between acute, right, and obtuse triangles using angle measurements
  • Apply the Pythagorean theorem to solve right triangle problems
  • Calculate missing angles using the 180-degree angle sum property
  • Determine triangle areas using base and height formulas
  • Solve real-world problems involving triangle properties and measurements

Understanding Types of Triangles

Complete explanation with examples

Properties of triangles

The triangle is a geometric figure with three sides that form three angles whose sum is always 180o 180^o degrees.

A - Properties of triangles

Its vertices are called A,B A,B and C C

The union between these vertices creates the edges AB,BC AB,BC and CA CA
There are several types of triangles that we will study in this article.

Detailed explanation

Practice Types of Triangles

Test your knowledge with 20 quizzes

Does the diagram show an obtuse triangle?

Examples with solutions for Types of Triangles

Step-by-step solutions included
Exercise #1

In a right triangle, the side opposite the right angle is called....?

Step-by-Step Solution

The problem requires us to identify the side of a right triangle that is opposite to its right angle.
In right triangles, one of the most crucial elements to recognize is the presence of a right angle (90 degrees).
The side that is directly across or opposite the right angle is known as the hypotenuse. It is also the longest side of a right triangle.
Therefore, when asked for the side opposite the right angle in a right triangle, the correct term is the hypotenuse.

Selection from the given choices corroborates our analysis:

  • Choice 1: Leg - In the context of right triangles, the "legs" are the two sides that form the right angle, not the side opposite to it.
  • Choice 2: Hypotenuse - This is the correct identification for the side opposite the right angle.

Therefore, the correct answer is Hypotenuse \text{Hypotenuse} .

Answer:

Hypotenuse

Exercise #2

In an isosceles triangle, what are each of the two equal sides called ?

Step-by-Step Solution

In an isosceles triangle, there are three sides: two sides of equal length and one distinct side. Our task is to identify what the equal sides are called.

To address this, let's review the basic properties of an isosceles triangle:

  • An isosceles triangle is defined as a triangle with at least two sides of equal length.
  • The side that is different in length from the other two is usually called the "base" of the triangle.
  • The two equal sides of an isosceles triangle are referred to as the "legs."

Therefore, each of the two equal sides in an isosceles triangle is called a "leg."

In our problem, we confirm that the correct terminology for these two equal sides is indeed "legs," distinguishing them from the "base," which is the unequal side. This aligns with both the typical definitions and properties of an isosceles triangle.

Thus, the equal sides in an isosceles triangle are known as legs.

Answer:

Legs

Exercise #3

In a right triangle, the two sides that form a right angle are called...?

Step-by-Step Solution

In a right triangle, there are specific terms for the sides. The two sides that form the right angle are referred to as the legs of the triangle. To differentiate, the side opposite the right angle is called the hypotenuse, which is distinct due to being the longest side. Hence, in response to the problem, the sides forming the right angle are correctly identified as Legs.

Answer:

Legs

Exercise #4

Does the diagram show an obtuse triangle?

Step-by-Step Solution

To determine if the triangle in the diagram is obtuse, we will visually assess the angles:

  • Step 1: Identify the angles in the diagram. The triangle has three angles, with one angle appearing between the horizontal base and the left slanted side.
  • Step 2: Evaluate the angle between the base and the left side. If it opens wider than a right angle, it's considered obtuse. This angle seems to be greater than 9090^\circ, indicating obtuseness.
  • Step 3: Conclude based on visual inspection. Since this key angle is greater than 9090^\circ, the triangle must be an obtuse triangle.

Therefore, the solution to the problem is Yes; the diagram does show an obtuse triangle.

Answer:

Yes

Video Solution
Exercise #5

Does the diagram show an obtuse triangle?

Step-by-Step Solution

To determine if the triangle shown in the diagram is obtuse, we proceed as follows:

  • Step 1: Identify that the diagram is indeed a triangle by observing the confluence of three edges forming a closed shape.
  • Step 2: Appreciate the geometric arrangement of the triangle, focusing on the sides' lengths and angles visually.
  • Step 3: Noticeably, the longest side of the triangle represents a noticeable tilt indicating the presence of an obtuse angle.

Based on the observation above, notably from the triangle's longest side against the base, it's clear that one angle is larger than 9090^\circ. Hence, the triangle in the diagram is indeed an obtuse triangle.

Therefore, the correct answer is Yes.

Answer:

Yes

Video Solution

Frequently Asked Questions

What are the 6 main types of triangles students need to know?

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The six main types are: 1) Equilateral (all sides equal), 2) Isosceles (two sides equal), 3) Scalene (all sides different), 4) Right (one 90° angle), 5) Acute (all angles less than 90°), and 6) Obtuse (one angle greater than 90°). These classifications help identify triangle properties and solve geometry problems.

How do you classify triangles by their sides?

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Triangles are classified by sides as follows: • Equilateral: All three sides are equal in length • Isosceles: Exactly two sides are equal in length • Scalene: All three sides have different lengths. Measuring and comparing side lengths is the key to this classification method.

What makes a triangle a right triangle?

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A right triangle has exactly one angle that measures 90 degrees (a right angle). The side opposite the right angle is called the hypotenuse and is always the longest side. Right triangles follow the Pythagorean theorem: a² + b² = c².

How do you find missing angles in triangles?

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Use the triangle angle sum property: all interior angles add up to 180°. To find a missing angle: 1) Add the two known angles, 2) Subtract this sum from 180°, 3) The result is your missing angle. For example: if two angles are 60° and 70°, the third angle is 180° - 60° - 70° = 50°.

What is the difference between acute and obtuse triangles?

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An acute triangle has all three angles measuring less than 90°. An obtuse triangle has exactly one angle measuring greater than 90°. The remaining two angles in an obtuse triangle must be acute (less than 90°) since all angles must sum to 180°.

How do you use the Pythagorean theorem with triangles?

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The Pythagorean theorem (a² + b² = c²) applies only to right triangles. 'a' and 'b' are the legs (shorter sides), and 'c' is the hypotenuse (longest side opposite the right angle). Use it to find missing side lengths when you know two sides of a right triangle.

Can you have a triangle with angles of 90°, 60°, and 40°?

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No, this is impossible. The angles 90° + 60° + 40° = 190°, which exceeds the required 180° sum for triangle interior angles. Valid triangle angles must always sum to exactly 180°, no more and no less.

What are the properties of an isosceles triangle?

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An isosceles triangle has: • Two sides of equal length • Two angles of equal measure (base angles) • One line of symmetry through the vertex angle • The equal angles are opposite the equal sides. These properties make isosceles triangles useful in many geometric proofs and real-world applications.

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