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.
Since the triangle is equilateral we know that its sides are equal, so we just divide the perimeter by three to get the measure of each side. lado.
P=3x
21cm=3x
x=21cm:3
Answer:
x=7cm
Example 4
Tell if it is possible to construct a triangle in which its sides measure 5cm, 7cm and 10cm.
Solution
We add the lengths of any two sides (edges) and compare with the length of the remaining side.
5cm+7cm=12cmwhich is greater than the remaining side that measures 10cm
7cm+10cm=17cmThe length of the remaining side, which is greater than the remaining side measuring 5cm, is greater than the remaining side measuring 5cm.
10cm+5cm=15cm, which is greater than the remaining side measuring 7cm.
Answer:
So if it is possible to construct a triangle of measures 5cm, 7cm and 10cm on each side.
Check your understanding
Question 1
What is the median of triangle ABC?
Incorrect
Correct Answer:
CF
Question 2
What is the median of triangle ABC.
Incorrect
Correct Answer:
There is no median shown.
Question 3
Look at the triangle ABC below.
Which of the following lines is the median of the triangle?
Incorrect
Correct Answer:
AD
Questions on the subject
How many sides does a triangle have?
A triangle has three sides.
How many edges does a triangle have?
A triangle has three edges.
What are the edges of a triangle?
The edges of a triangle, commonly called the sides of a triangle, are the straight lines that bound the faces of the triangle.
What are the edges of a figure?
In a plane figure, the edges or sides are the line segments that join two vertices, and form the outline or perimeter of the figure.
Exercises on the sides or edges of a triangle
Exercise 1
Query
DE Does that side not exist as part of any of the triangles?
Solution
A side in a triangle is a line that passes between one of the 3 points that are the angles of the triangle.
In this case the line DE does not pass between the extreme angles of any of the triangles but goes out through a point D which is in fact an angle in a triangle △DBC but DE ends at the point E which is not an angle in any of the triangles in the figure.
Answer
True
Do you think you will be able to solve it?
Question 1
Look at the triangle ABC below.
Which of the line segments is the median?
Incorrect
Correct Answer:
FC
Question 2
Fill in the blanks:
In an isosceles triangle, the angle between two ___ is called the "___ angle".
Incorrect
Correct Answer:
sides, main
Question 3
In an isosceles triangle, the angle between ? and ? is the "base angle".
Incorrect
Correct Answer:
Side, base.
Exercise 2
Question:
Do the triangles in the drawing overlap?
Solution
We can observe that according to the theorem of superposition: side, side, angle.
We can observe that there are 2 sides equal in length and an angle equal in size.
Answer
Yes
Exercise 3
Question
What type of triangle is drawn here?
Solution
It can be seen that in this triangle each of its three angles is of different size so it can be said that it is a scalene triangle.
Answer
Scalene triangle
Test your knowledge
Question 1
In an isosceles triangle, the third side is called?
Incorrect
Correct Answer:
Base
Question 2
Look at the two triangles below.
Is CB a side of one of the triangles?
Incorrect
Correct Answer:
Yes.
Question 3
Is DE side in one of the triangles?
Incorrect
Correct Answer:
Not true
Exercise 4
Consigna
Given the following triangle:
The perimeter of the triangle is 17
How much is X?
Solution
To solve the task we replace all the data we have in the equation to calculate the perimeter of the triangle:
2X+3X+3.5X=17
Let's remember... The perimeter of the triangle is equal to the sum of its 3 sides.
If we calculate the equation we find that:
8.5X=17
We divide the equation by 8.5 to find the value of. X
8.58.5X=X=8.517=2
Answer
2
Exercise 5
Request
Given the equilateral triangle
The perimeter of the triangle is 33cm, what is the value of X?
Solution
One of the characteristics of an equilateral triangle is obviously that each of its sides are equal, i.e. if one side is worth 11 all its sides will be equal to 11
Answer
11
Do you know what the answer is?
Question 1
The triangle ABC is shown below.
To which side(s) are the median and the altitude drawn?
Incorrect
Correct Answer:
BC
Question 2
Look at triangle ABC below.
What is the median of the triangle and to which side is it drawn?
Incorrect
Correct Answer:
BE for AC
Question 3
Look at triangle ABC below.
Which is the median?
Incorrect
Correct Answer:
EC
Examples with solutions for The sides or edges of a triangle
Exercise #1
Is DE side in one of the triangles?
Video Solution
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
Exercise #2
The triangle ABC is shown below.
To which side(s) are the median and the altitude drawn?
Step-by-Step Solution
To solve the problem of identifying to which side of triangle ABC the median and the altitude are drawn, let's analyze the diagram given for triangle ABC.
We acknowledge that a median is a line segment drawn from a vertex to the midpoint of the opposite side. An altitude is a line segment drawn from a vertex perpendicular to the opposite side.
Upon reviewing the diagram of triangle ABC, line segment AD is a reference term. It appears to meet point C in the middle, suggesting it's a median, but it also forms right angles suggesting it is an altitude.
Given the placement and orientation of AD, it is perpendicular to line BC (the opposite base for the median from A). Therefore, this line is both the median and the altitude to side BC.
Thus, the side to which both the median and the altitude are drawn is BC.
Therefore, the correct answer to the problem is the side BC, corresponding with choice Option 2: BC.
Answer
BC
Exercise #3
Look at triangle ABC below.
What is the median of the triangle and to which side is it drawn?
Step-by-Step Solution
A median of a triangle is a line segment that connects a vertex to the midpoint of the opposite side. In triangle △ABC, we need to identify such a median from the diagram provided.
Step 1: Observe the diagram to identify the midpoint of each side.
Step 2: It is given that point E is located on side AC. If E is the midpoint of AC, then any line from a vertex to point E would be a median.
Step 3: Check line segment BE. This line runs from vertex B to point E.
Step 4: Since E is labeled as the midpoint of AC, line BE is the median of △ABC drawn to side AC.
Therefore, the median of the triangle is BE for AC.
Answer
BE for AC
Exercise #4
Look at triangle ABC below.
Which is the median?
Step-by-Step Solution
To solve this problem, we must identify which line segment in triangle ABC is the median.
First, review the definition: a median in a triangle connects a vertex to the midpoint of the opposite side. Now, in triangle ABC:
Point A represents the vertex.
Point E lies on line segment AB.
Line segment EC needs to be checked to see if it connects vertex E to point C.
From the diagram, it appears that E is indeed the midpoint of side AB. Thus, line segment EC connects vertex C to this midpoint.
This fits the definition of a median, verifying that EC is the median line segment in triangle ABC.
Therefore, the solution to the problem is: EC.
Answer
EC
Exercise #5
Look at the triangle ABC below.
AD=21AB
BE=21EC
What is the median in the triangle?
Step-by-Step Solution
A median in a triangle is a line segment connecting a vertex to the midpoint of the opposite side. Here, we need to find such a segment in triangle △ABC.
Let's analyze the given conditions:
AD=21AB: Point D is the midpoint of AB.
BE=21EC: Point E is the midpoint of EC.
Given that D is the midpoint of AB, if we consider the line segment DC, it starts from vertex D and ends at C, passing through the midpoint of AB (which is D), fulfilling the condition for a median.
Therefore, the line segment DC is the median from vertex A to side BC.