Triangles-Notes



          



Class X Math
Notes for Triangles
Basic Concepts with Examples
•    SIMILAR TRIANGLES. Two triangles are said to be similar if
       (i)   their corresponding angles are equal and
       (ii)  their corresponding sides are proportional.
•    All congurent triangles are similar but the similar triangles need not be congruent.
•    Two polygons of the same numbers of sides are similar, if
       (i)   their corresponding angles are equal and
       (ii)  their corresponding sides are in the same ratio.
•    BASIC PROPORTIONALITY THEOREM. In a triangle, a line drawn parallel to one side, to intersect the other sides in distinct points, divides the two sides in the same ratio.
•    CONVERSE OF BASIC PROPORTIONALITY THEOREM. If a line divides any two sides of a triangle in the same ratio, the line must be parallel to the third side.