A triangle is composed of three line segments. The heat segments crossing in their endpoints. To name a triangle we frequently use its vertices (the surname of the endpoints). The triangle below is named ABC.

You are watching: One obtuse angle and no congruent sides

A triangle has actually three angles. The sum of the procedures of the angles is always 180° in a triangle.

We have actually different species of triangles. A triangle is classified by that is angles and by the number of congruent sides.

A triangle that has actually three acute angels is dubbed an acute triangle.

A triangle that has actually one ideal angle is dubbed a right triangle.

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

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

When a triangle has actually two congruent sides it is referred to as an isosceles triangle. The angles opposite to the 2 sides of the same size are congruent.

A triangle without any congruent political parties or angle is dubbed a scalene triangle.

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When two triangles are congruent it means that they have actually the very same size and also shape. This means that they have actually the exact same angles. The red cut marks present us which sides and also angles that space congruent Congruency is presented by this symbol

\$\$cong\$\$

\$\$eginmatrix Acong X & & ABcong XY\ Bcong Y & & BCcong YZ\ Ccong Z & & ACcong XZ endmatrix\$\$

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

\$\$sim\$\$

\$\$igtriangleup ABCsim igtriangleup XYZ\$\$

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

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

Example

Find x in the comparable triangles.

We recognize that due to the fact that the triangles are similar the sides room proportional which method that

\$\$fracx14=frac321Rightarrow\$\$

\$\$x=frac14cdot 321=frac4221=2\$\$

\$\$x=2\$\$

## Video lesson

Find the end whether the triangles space right, isosceles, acute, scalene, obtuse or equilateral