Prove that the line joining the midpoints of any two sides of a triangle is parallel to the third side.

Using Theorem , prove that the line joining the mid-point of any two sides of a triangle is parallel to the third side. ( Recall that you have done it is class IX) .

In a trapezium, prove that the line joining the midpoints of non - parallel sides are parallel to the parallel sides of the trapezium.

Using Theorem , prove that a line drawn thought the mid- point of one side of a triangle parallel to another side bisects the third side .( Recall that you have proved it in class IX).

Show that the line segments joining the mid-points of the opposite sides of a quadrilateral bisect each other.

Show tha the line segments joining the mid points of the opposite sides of a quadrilateral bisect each other.

Show that the figure formed by joining the midpoints of sides of a rhombus successively is a rectangle.

Prove that “the ratio of the areas of two similar triangles is equal to the square of the ratio of their corresponding sides”.

If a straight line divdes two sides of a triangle proportionally, then the straight line a parallel to third sides, (Converse of Thales theorem). Prove.

"If the square on the longest sides of a triangle is equal to the sum of the squares on the other two sides then those two sides contain a right angle." Prove.

The vertices of a Delta ABC are A (-5,-1), B (3,-5) , C (5,2). Show that the area of the Delta ABC is four times the area of the triangle formed by joining the mid-points of the sides of the triangle ABC.