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SAI International School
CLASS - X

Mathematics
CHAPTER-6: Triangles-1Lesson Notes-1

SUBTOPIC : Similar Triangles,BPT & its Converse

*Congruent Figure: Two figures are said to be congruent if they have the same
shape and same size in all respect.

Example:*Two circles are congruent if they have same radii.

*Two squares are congruent if each side of these two are equal.

*Two rectangles are congruent if its length and breadth are equal.

*Two triangles are congruent if 6 corresponding parts(3sides and 3 angles) of a
triangle are equal to 6 corresponding parts of another triangle.


* ABC   DEF if AB=DE, BC=EF, AC=DF & A   D  B   E  C   F
,
,
*Congruence Criterion: It is verified that if 3 specific corresponding parts of one
triangle are equal to 3 specific corresponding parts of another triangle are equal then
other 3 corresponding parts are going to be equal. These specific conditions are
called Congruence Criterion of Triangles.

*Two triangles are said to be congruent if :

SSS: 3 sides of a triangle are equal to 3 sides of another triangle are equal.

SAS: 2 sides and included angle of a triangle are equal to 2 sides and included
angle are equal

ASA: Two angles and included side of a triangle are equal to two angles and
included side of a triangle are equal

AAS: Any two angles and one side of a triangle are equal to any two angles and one
side of a triangle are equal.

RHS:(for right angled triangle) Right angle-Hypotenuse-Side: Hypotenuse and any
side of a right angled triangle are equal to hypotenuse and any side of other right
angled triangle.
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