Parts of a Triangle Practice Problems - Sides, Perimeter & Types

Master triangle parts with interactive practice problems. Learn to identify sides, calculate perimeter, classify triangle types, and apply the triangle inequality theorem.

📚Master Triangle Parts with Step-by-Step Practice
  • Calculate triangle perimeter by adding all three sides together
  • Classify triangles as equilateral, isosceles, or scalene based on side lengths
  • Apply the triangle inequality theorem to determine valid triangle formations
  • Identify relationships between side lengths and opposite angles
  • Solve for unknown side lengths in equilateral triangles using perimeter
  • Determine if three given measurements can form a valid triangle

Understanding The sides or edges of a triangle

Complete explanation with examples

The sides of a triangle

Every triangle has three sides. That also works the other way around - if we see a shape with tree sides, it's a triangle.

types of triangles based on the sides:

The sides allow us to classify the different types of triangles according to their size:

  • Equilateral: All sides are equal, leading to equal angles.
  • Isosceles: Two sides are equal, with base angles also equal.
  • Scalene: All sides are different lengths, with all angles unique.
Perimeter of a Triangle

Like every polygon, the sides of a triangle form its perimeter. To find the perimeter of a triangle, simply add the lengths of all three sides.

A1 - Sides of a triangle
Relation between the sides and the angles in a triangle

In a triangle, there’s a direct relationship between the length of a side and the size of the angle across from it:
The Longer Side will always be in the opposite side of the larger Angle, and the shorter side will always be in the opposite side of the smaller Angle.

Can every three lines form a triangle?

In any triangle, the sum of the two shorter sides must always be greater than the length of the third side. This rule, known as the Triangle Inequality Theorem, ensures that the sides can actually form a closed triangle. For example, if the two shorter sides are not greater than the third, the sides would lie flat rather than forming a triangle. This principle is crucial in determining whether a set of side lengths can create a valid triangle.

Detailed explanation

Practice The sides or edges of a triangle

Test your knowledge with 36 quizzes

Is the straight line in the figure the height of the triangle?

Examples with solutions for The sides or edges of a triangle

Step-by-step solutions included
Exercise #1

Determine the type of angle given.

Step-by-Step Solution

To solve this problem, we'll examine the image presented for the angle type:

  • Step 1: Identify the angle based on the visual input provided in the graphical representation.
  • Step 2: Classify it using the standard angle types: acute, obtuse, or straight based on their definitions.
  • Step 3: Select the appropriate choice based on this classification.

Now, let's apply these steps:

Step 1: Analyzing the provided diagram, observe that there is an angle formed among the segments.

Step 2: The angle is depicted with a measure that appears greater than a right angle (greater than 9090^\circ). It is wider than an acute angle.

Step 3: Given the definition of an obtuse angle (greater than 9090^\circ but less than 180180^\circ), the graphic clearly shows an obtuse angle.

Therefore, the solution to the problem is Obtuse.

Answer:

Obtuse

Video Solution
Exercise #2

Given the following triangle:

Write down the height of the triangle ABC.

AAABBBCCCDDD

Step-by-Step Solution

To resolve this problem, let's focus on recognizing the elements of the triangle given in the diagram:

  • Step 1: Identify that ABC \triangle ABC is a right-angled triangle on the horizontal line BC, with a perpendicular dropped from vertex A A (top of the triangle) to point D D on BC BC , creating two right angles ADB \angle ADB and ADC \angle ADC .
  • Step 2: The height corresponds to the perpendicular segment from the opposite vertex to the base.
  • Step 3: Recognize segment BD BD as described in the choices, fitting the perpendicular from A to BC in this context correctly.

Thus, the height of triangle ABC \triangle ABC is effectively identified as segment BD BD .

Answer:

BD

Video Solution
Exercise #3

Given the following triangle:

Write down the height of the triangle ABC.

AAABBBCCCDDD

Step-by-Step Solution

To determine the height of triangle ABC \triangle ABC , we need to identify the line segment that extends from a vertex and meets the opposite side at a right angle.

Given the diagram of the triangle, we consider the base AC AC and need to find the line segment from vertex B B to this base.

From the diagram, segment BD BD is drawn from B B and intersects the line AC AC (or its extension) perpendicularly. Therefore, it represents the height of the triangle ABC \triangle ABC .

Thus, the height of ABC \triangle ABC is segment BD BD .

Answer:

BD

Video Solution
Exercise #4

Given the following triangle:

Write down the height of the triangle ABC.

AAABBBCCCEEEDDD

Step-by-Step Solution

An altitude in a triangle is the segment that connects the vertex and the opposite side, in such a way that the segment forms a 90-degree angle with the side.

If we look at the image it is clear that the above theorem is true for the line AE. AE not only connects the A vertex with the opposite side. It also crosses BC forming a 90-degree angle. Undoubtedly making AE the altitude.

Answer:

AE

Video Solution
Exercise #5

Given the following triangle:

Write down the height of the triangle ABC.

AAABBBCCCDDD

Step-by-Step Solution

To solve this problem, we need to identify the height of triangle ABC from the diagram. The height of a triangle is defined as the perpendicular line segment from a vertex to the opposite side, or to the line containing the opposite side.

In the given diagram:

  • A A is the vertex from which the height is drawn.
  • The base BC BC is a horizontal line lying on the same level.
  • AD AD is the line segment originating from point A A and is perpendicular to BC BC .

The perpendicularity of AD AD to BC BC is illustrated by the right angle symbol at point D D . This establishes AD AD as the height of the triangle ABC.

Considering the options provided, the line segment that represents the height of the triangle ABC is indeed AD AD .

Therefore, the correct choice is: AD AD .

Answer:

AD

Video Solution

Frequently Asked Questions

How do you find the perimeter of a triangle?

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To find the perimeter of a triangle, simply add the lengths of all three sides together. For example, if a triangle has sides of 4 cm, 3 cm, and 5 cm, the perimeter is 4 + 3 + 5 = 12 cm.

What are the three types of triangles based on their sides?

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The three types are: 1) Equilateral - all three sides are equal, 2) Isosceles - two sides are equal, 3) Scalene - all three sides are different lengths. Each type also has corresponding angle properties.

What is the triangle inequality theorem?

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The triangle inequality theorem states that the sum of any two sides of a triangle must be greater than the length of the third side. This rule determines whether three given lengths can actually form a valid triangle.

How do you check if three sides can form a triangle?

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Check all three combinations: add the two shorter sides and verify the sum is greater than the longest side. For example, with sides 5, 7, and 10: check that 5+7>10, 7+10>5, and 5+10>7.

What is the relationship between triangle sides and angles?

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In any triangle, the longest side is always opposite the largest angle, and the shortest side is opposite the smallest angle. This direct relationship helps identify angle sizes based on side lengths.

How do you find the side length of an equilateral triangle from its perimeter?

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Since all three sides are equal in an equilateral triangle, divide the perimeter by 3. For example, if the perimeter is 21 cm, each side is 21 ÷ 3 = 7 cm.

Can a triangle have sides of 3 cm, 4 cm, and 8 cm?

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No, these sides cannot form a triangle. When you add the two shorter sides (3 + 4 = 7), the sum is less than the third side (8 cm), violating the triangle inequality theorem.

What are the parts of a triangle?

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A triangle has three main parts: three sides (edges), three vertices (corners), and three angles. The sides connect the vertices and form the perimeter, while angles are formed where two sides meet.

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