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 33 quizzes

Given the following triangle:

Write down the height of the triangle ABC.

AAABBBCCCDDD

Examples with solutions for The sides or edges of a triangle

Step-by-step solutions included
Exercise #1

Is DE side in one of the triangles?
AAABBBCCCDDDEEE

Step-by-Step Solution

Since line segment DE does not correspond to a full side of any of the triangles present within the given geometry, we conclude that the statement “DE is a side in one of the triangles” is Not true.

Answer:

Not true

Video Solution
Exercise #2

Determine the type of angle given.

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Examine the diagram presented.
  • Step 2: Identify any familiar angle formations or configurations.
  • Step 3: Use knowledge of angles to classify the type shown.
  • Step 4: Determine the correct response from available options.

Observing the diagram:

The diagram includes two lines, one horizontal and the other vertical, extending fully. This horizontal extent along with the linear continuation suggests it forms an angle at the intersection with 180180^\circ. This indicates a straight angle.

We classify straight angles because an angle formed by two lines directly facing opposite directions is known to measure 180180^\circ. This diagrammatic representation aligns perfectly to confirm it calculates and visually shows a straight angle.

Thus, by recognizing these details within the diagram, we confirm the type of angle as Straight.

Answer:

Right

Video Solution
Exercise #3

Determine the type of angle given.

Step-by-Step Solution

The problem involves classifying the angle represented visually, which looks like a semicircle with a central axis drawn. This indicates an angle that spans half a complete circle.

A complete circle measures 360360^\circ, so half of it, represented by a semicircle, measures half of 360360^\circ, which is 180180^\circ.

The four primary classifications for angles are:

  • Acute: Less than 9090^\circ
  • Right: Exactly 9090^\circ
  • Obtuse: Greater than 9090^\circ but less than 180180^\circ
  • Straight: Exactly 180180^\circ

Since the angle measures exactly 180180^\circ, it is classified as a straight angle.

Therefore, the type of angle given is Straight.

Answer:

Straight

Video Solution
Exercise #4

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

Step-by-Step Solution

The task is to determine whether the line shown in the diagram serves as the height of the triangle. For a line to be considered the height (or altitude) of a triangle, it needs to be a perpendicular segment from a vertex to the line that contains the opposite side, often referred to as the base.

Let's analyze the diagram:

  • The triangle is described by its vertices, forming a shape, and one side is the base. There's a line drawn from one vertex directed toward the opposite side.
  • To be the height, this line must be perpendicular to the side it meets (the base).
  • Though the figure does not explicitly show perpendicularity with a right angle mark, the line appears as a straight, direct connection from the vertex to the base. This is typically indicative of it being a height.
  • Assuming typical geometric conventions and the common depiction of heights in diagrams, the line shows properties consistent with being perpendicular to the opposite side, thereby functioning as the height.

Based on the analysis, the line is indeed the height of the triangle. Thus, the answer is Yes.

Therefore, the solution to the problem is Yes.

Answer:

Yes

Video Solution
Exercise #5

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

Step-by-Step Solution

To determine if the straight line in the figure is the height of the triangle, we must verify the following:

  • The line segment must extend from a vertex of the triangle and be perpendicular to the opposite side (or its extension).

In examining the figure provided, we notice that the triangle is formed by vertices at points A,B, A, B, and C C . Let's assume the base is the line segment BC \overline{BC} .

The line in question extends from a vertex A A and appears to intersect the base BC BC at a right angle.

  • Since it is extending from vertex to the opposite side and forming a right angle with it, this line meets the definition of an altitude.

Therefore, the line in the figure is indeed the height of the triangle. By confirming the perpendicular relationship, we determine that this geometric feature correctly describes an altitude.

Yes, the straight line in the figure is the height of the triangle.

Answer:

Yes

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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