A triangle is created of three line segments. The line segments intersect in your endpoints. To name a triangle we frequently use that vertices (the surname of the endpoints). The triangle listed below is named ABC.

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A triangle has three angles. The amount of the actions of the angles is constantly 180° in a triangle.

We have actually different types of triangles. A triangle is classified by the angles and by the variety of congruent sides.

A triangle that has three acute angels is referred to as an acute triangle.

A triangle that has actually one best angle is dubbed a appropriate triangle.

A triangle that has actually one obtuse edge is referred to as an obtuse triangle.

When a triangle has three congruent sides, we call the triangle an it is provided triangle. We note the congruent political parties by a slash mark. The angles in an it is intended triangle are constantly 60°.

When a triangle has actually two congruent political parties it is called an isosceles triangle. The angle opposite to the 2 sides of the same size are congruent.

A triangle without any congruent sides or angles is dubbed a scalene triangle.

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When two triangles space congruent it method that they have the exact same size and shape. This method that they have the same angles. The red cut marks display us i m sorry sides and also angles that space congruent Congruency is displayed by this symbol

$$\\cong$$

$$\\beginmatrix A\\cong X & & AB\\cong XY\\\\ B\\cong Y & & BC\\cong YZ\\\\ C\\cong Z & & AC\\cong XZ \\endmatrix$$

Triangles that have congruent angles yet not the same size are dubbed similar. Comparable triangles have sides that are proportional. Similarity is displayed by this symbol

$$\\sim$$

$$\\bigtriangleup ABC\\sim \\bigtriangleup XYZ$$

$$A=X,\\: \\: B=Y,\\: \\: C=Z$$

$$\\fracax=\\fracby=\\fraccz$$

Example

Find x in the similar triangles.

We recognize that due to the fact that the triangle are comparable the sides room proportional which method that

$$\\fracx14=\\frac321\\Rightarrow$$

$$x=\\frac14\\cdot 321=\\frac4221=2$$

$$x=2$$

## Video lesson

Find out whether the triangles are right, isosceles, acute, scalene, obtuse or equilateral