

SSS Congruence: Definition, Rules, and Detailed Example
What are Congruent Triangles?
A polygon is generally made of three line segments that form three angles known as a Triangle.
Two triangles are known to be congruent triangles if their sides have equal length and the angles in the triangle have the same measure. Therefore, any two triangles can be superimposed side to side and also angle to angle.
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In the figure given below, Δ ABC and Δ PQR are known to be congruent triangles. This means that ,
Vertices: A and P, B and Q, and C and R are the same.
Sides: AB is equal to PQ, QR is equal to BC and AC is equal to PR;
Angles: ∠A equals ∠P, ∠B equals ∠Q, and ∠C equals ∠R.
Congruent triangles are known to be the triangles that have corresponding sides and angles are known to be equal. Congruence is basically denoted by the symbol ≅. They have the same area and have the same perimeter.
What are the Rules of Congruency?
There are four main rules of congruence for triangles:
SSS Criterion: Side-Side-Side -Two triangles are known to be congruent if all the sides of any given triangle are equal in measure to all the corresponding sides of the other triangle.
SAS Criterion: Side-Angle-Side-Two triangles are known to be congruent if two sides and the included angle of one of the triangles are equal to the two sides and the included angle of the other triangle.
ASA Criterion: Angle-Side- Angle - Two triangles are known to be congruent if two angles and the included side of one of the triangles are equal to two angles and the included side of another triangle.
RHS Criterion: Right angle- Hypotenuse-Side
In this article we are going to discuss the SSS congruence & constructing triangles with sss congruence.
SSS Congruence Rule: If three sides of 1 triangle are similar to the corresponding sides of another triangle, then the triangles are known to be congruent. Constructing triangles with sss congruence criteria is possible when all the three sides are known to us. The necessities of constructing triangles with sss congruence are basically a ruler and a compass. Side-Side-Side is one among the properties of similar triangles.
How to Construct a Triangle with the Given Three Sides?
By the SSS(Side,Side,Side) rule, construction of a triangle is easily possible with three given side measures. For the construction of a triangle, you need to first identify the longest measure among the three side measures. Now, draw the longest side measure because of the base of the triangle, then take other measurements using a ruler to mark the arcs by taking the endpoints of the bottom as vertices. Finally, now you need to join the intersection of arcs with the endpoints of the base to get the specified triangle
Now, you may run into a "trick" question where the given segments will NOT form a triangle. You need to keep in mind that the sum of the lengths of any two sides of a triangle must be greater than the length of the third side of the triangle. If this relationship does not occur, then you will NOT be able to draw a triangle.
Therefore this is how to construct a triangle with the given three sides.
Constructing SSS Triangles
Let us consider a triangle namely ABC, having the measurement of sides equal:
Side AB = 7 cm, Side BC = 4 cm and Side CA = 6 cm. Now the steps for construction of triangle are:
Step 1: First mark a point namely A
Step 2: Now you need to measure a length of 7 cm using compass and a ruler
Step 3: With the help of a compass and then mark an arc placing pointer at a point namely A
Step 4: Mark a point named B on the arc
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Step 5: Now measure the length of six(6) cm
Step 6: Now again using compass mark an arc above the point B using the same point namely (A)
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Step 7: Measure a length equal to 4 cm
Step 8: Now using the compass placed at point namely B cut an arc such that it crosses the previous arc.
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Step 9: Now the name the point as C, which is the point where the two arcs cross each other
Step 10: At the end,you need to join the points A, B and C with the help of a ruler to get the required triangle.
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Thus, the obtained triangle given above is the required triangle ABC with the given measurements.
Questions to be Solved :
Question 1) List down the steps for constructing sss triangles.
Solution) Constructing SSS Triangles
Let us consider a triangle namely ABC, having the measurement of sides equal:
Side AB = 7 cm, Side BC = 4 cm and Side CA = 6 cm. Now the steps for constructing triangles sss are:
Step 1: First mark a point namely A
Step 2: Now you need to measure a length of 7 cm using compass and a ruler
Step 3: With the help of a compass and then mark an arc placing pointer at a point namely A
Step 4: Mark a point named B on the arc
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Step 5: Now measure the length of six (6) cm
Step 6: Now again using compass mark an arc above the point B using the same point namely (A)
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Step 7: Measure a length equal to 4 cm
Step 8: Now using the compass placed at point namely B cut an arc such that it crosses the previous arc.
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Step 9: Now the name the point as C, which is the point where the two arcs cross each other
Step 10: At the end,you need to join the points A, B and C with the help of a ruler to get the required triangle.
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Thus, the obtained triangle shown above is the required triangle ABC with the given measurements.
FAQs on How to Construct SSS Congruent Triangles: Easy Steps
1. What is the SSS (Side-Side-Side) Congruence Rule for triangles?
The SSS (Side-Side-Side) Congruence Rule states that if the three sides of one triangle are equal in length to the three corresponding sides of another triangle, then the two triangles are congruent. This means they have the exact same size and shape, and all their corresponding angles will also be equal.
2. What condition must the side lengths satisfy to construct a triangle using the SSS criterion?
To construct a unique triangle with three given side lengths, a crucial condition known as the Triangle Inequality Theorem must be met. This theorem states that the sum of the lengths of any two sides of a triangle must be greater than the length of the third side. If this condition is not satisfied, the sides will not connect to form a closed triangle.
3. How do you construct a triangle when the lengths of all three sides are given (SSS)?
To construct a triangle using the SSS criterion, follow these steps using a ruler and compass:
- Step 1: Draw a line segment that is the length of one of the sides, let's say side AB.
- Step 2: With the compass point at A, set its width to the length of the second side (AC) and draw an arc.
- Step 3: With the compass point at B, set its width to the length of the third side (BC) and draw another arc that intersects the first one.
- Step 4: Label the intersection point as C. Join points A to C and B to C to complete the triangle ΔABC.
4. Can you provide a step-by-step example of constructing a triangle with sides 5 cm, 6 cm, and 7 cm?
Certainly. To construct ΔPQR with PQ = 6 cm, QR = 7 cm, and PR = 5 cm:
- First, draw the base line segment PQ = 6 cm.
- Next, place your compass point on P and draw an arc with a radius of 5 cm (the length of PR).
- Then, place your compass point on Q and draw another arc with a radius of 7 cm (the length of QR).
- The point where these two arcs intersect is R.
- Finally, join P to R and Q to R. You have now constructed ΔPQR with the given SSS measurements.
5. Why is the SSS rule sufficient to prove that two triangles are congruent?
The SSS rule is sufficient because the lengths of the three sides completely fix the shape and size of a triangle. Once the side lengths are defined, the angles between them are also fixed, even though they are not measured directly. Any attempt to change an angle would require changing the length of at least one side. Therefore, if two triangles have identical side lengths, all their corresponding angles must also be identical, making them geometrically rigid and congruent.
6. What happens if you try to construct a triangle with sides 3 cm, 4 cm, and 8 cm? Why does the SSS construction fail?
The SSS construction will fail for sides 3 cm, 4 cm, and 8 cm because it violates the Triangle Inequality Theorem. Here, the sum of the two smaller sides (3 cm + 4 cm = 7 cm) is not greater than the third side (8 cm). When you draw the base of 8 cm and then draw arcs of 3 cm and 4 cm from its endpoints, the arcs will be too short to ever intersect. This demonstrates that it's impossible to form a closed triangle with these side lengths.
7. How is constructing a triangle using SSS different from using SAS (Side-Angle-Side)?
The key difference lies in the given information. For SSS construction, you are given the lengths of all three sides. For SAS construction, you are given the lengths of two sides and the measure of the included angle (the angle between those two sides). The construction process differs accordingly: in SAS, you draw one side, then construct the given angle at one endpoint before drawing the second side along that angle's ray.
8. Where is the principle of SSS congruence used in real-world applications?
The principle of SSS congruence is fundamental to creating rigid and stable structures. Its main application is in engineering and architecture. For example:
- Bridges and Trusses: Triangular trusses are used in bridges and roofs because a triangle is a rigid shape. SSS congruence ensures that each triangular unit is identical and strong.
- Manufacturing: In mass production of items with triangular components, SSS ensures that all parts are identical and interchangeable.
- Geodesic Domes: These structures are networks of interconnected triangles that create a strong, spherical shape.





