**Important Concepts and Formulas**

1. Perpendicular distance between two
parallel lines at every point remains the same.

2. There can be many lines parallel to a
given line.

3. From a given point, one and only one
line can be drawn parallel to a given line.

4. A unique triangle can be constructed
if

·
its
three sides are known.

·
the
lengths of any two sides and the measure of the included angle are known.

·
the
measures of two angles and the length of the side including them are known.

·
the
length of one leg and the hypotenuse of a right-angled triangle are known.

To see the construction of different types of triangles ----- Click Here!

To see the construction of different types of triangles ----- Click Here!