Wednesday, September 26, 2012

Geometry Triangle Congruence

Triangle is a polygon with three sides.Congruent triangles are special types of similar triangle which have both shape and size equal. If one triangle is placed on the other triangle it is fitted correctly on the first triangle.Two triangles are congruent if all parts of both the triangles are the same.

A triangle has 6 parts

3 sides
3 angles
So when two triangles are congruent all the 6 parts are congruent .

Introduction to geometry triangle Congruence:
In  two dimensional Plane Geometry, two triangles are congruent if all the corresponding parts of those triangles are similar.  The corresponding sides of two triangles are equal in measure and their corresponding angles are equal in degrees, we can say the two triangles are congruent.If triangle PQR is congruent to triangle XYZ, the relationship between these two triangles can be written as:?PQR `~=` ?XYZ

Congruence of Triangles in Geometry:
Postulates based on congruence of triangles:

Angle Angle Angle (AAA)

Side Side Side (SSS)

Side Angle Side (SAS)

Angle-Angle-Side(AAS)

Right-angle-Hypotenuse-Side(RHS)

Angle Angle Angle (AAA):

When three angles of the two triangles are equal, we can say that the two triangles are similar triangles.That is the corresponding angles have same measures.

Side Side Side (SSS):

When all three sides of both the triangles are equal, we can say that the triangles are similar triangles.

Side Angle Side (SAS):

When two sides in one triangle are equal to corresponding sides of the other triangle, and the included angles are equal, we can say that both are congruent triangle.

Angle-Angle-Side (AAS):

When two pairs of angles of two triangles are equal in measurement, and pair of corresponding unincluded sides are equal in length, then the triangles are called as congruent triangle.

Right-angle-Hypotenuse-Side (RHS):

When two right-angled triangles with their hypotenuses equal in length, and the shorter sides of two right triangles are equal in length, then the triangles are called as congruent triangle.


Properties of Congruence Triangles in Geometry:

If two triangles are congruent triangles in geometry, then each side or angle of the triangle is congruent to the corresponding part in the other triangle. Once if we proved two triangles are congruent, we can find the angles or sides of one of them from the other triangle.

To remember this we use the acronym CPCTC, which is expressed as “Corresponding Parts of Congruent Triangles are Congruent". In addition with sides and angles of two triangle, all other properties such as area, perimeter, location of centers, circles etc. of the triangle are the same.

Between, if you have problem on these topics help on math homework, please browse expert math related websites for more help on help with solving math problems.

Example Based on Congruency of Triangles in Geometry:
Ex : 1From the figure state that the triangles are congruent or not . If congruent by which postulate


Sol:From figure
QR = 4cm = TV

PR = 5cm = SV

Two sides and the included angle are congruent

So by SAS postulate the triangles are congruent.

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