Class 6 Triangle
Isosceles Right-Angle Triangle
Triangle
If P, Q, R are three non-collinear points, the figure made up by three line segments PQ, QR and RP is known as triangle with P, Q and R as vertices.
We shall use the symbol △ PQR to denote the triangle. The three line segments PQ, QR and RP are called the sides of the triangle.
The three angles ∠RPQ , ∠PQR, and ∠QRP are known as angles of the triangle. We can denote this angles as ∠P, ∠Q and ∠R respectively.
There are various types of tringles as mentioned below.
- Equilateral Triangle
- Isosceles Triangle
- Scalene Triangle
- Acute Triangle
- Right Triangle
- Zero angle
- Obtuse Triangle
- Isosceles Right-Angle Triangle
Equilateral Triangle
A triangle whose all sides are equal is known as equilateral triangle.
Isosceles Triangle
A triangle whose two sides are equal is known as isosceles triangle.
Scalene Triangle
A triangle whose no two sides are equal is known as scalene triangle.
Acute Triangle
A triangle whose each angle is less than 90° is known as acute triangle.
Right Triangle
A triangle whose one angle is equal to 90° is known as right angled triangle or right triangle.
Obtuse Triangle
A triangle whose one angle is more than 90° is known as obtuse triangle.
Isosceles Right-Angle Triangle
A triangle whose one angle is equal to 90° and it's two sides are equal then it is known as isosceles right angle triangle.
Perimeter of a triangle
The sum of the lengths of the sides of a triangle is known as it's perimeter.
Example 1. Find the perimeter of the below triangle.
Solution. PQ = 5cm, PR = 4 cm and QR = 7 cm
Perimeter = PQ + PR + QR
= 5 + 4 + 7 = 16 cm
So, the perimeter of the triangle is 16 cm.
Example 2. Find the perimeter of the below triangle.
Solution. XY = 3cm, YZ = 5 cm and ZX = 5 cm
Perimeter = XY + YZ + ZX
= 3 + 5 + 5 = 13 cm
So, the perimeter of the triangle is 13 cm.
Properties of Triangle
1. If all the angles in a triangle are equal, then its sides are equal.
2. If all the sides of a triangle are equal, then angles are also equal.
3. If two angles of a triangle are equal, then it has two equal sides.
4. If two sides of a triangle are equal, then its two angles are also equal.
5. If none of the angles of a triangle are equal, then none of the sides are equal.
6. The sum of all the angles of a triangle is equal to 180°.
7. The sum of lengths of any two sides is greater than the length of the third side.
Class-6 Triangle Test
Class-6 Triangle Worksheet
Answer Sheet
Triangle-AnswerDownload the pdf
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