If the quadrilateral formed by joining the mid-points of the adjacent sides of quadrilateral ABCD is a rectangle, show that the diagonals AC and BD intersect at right angle.

The midpoint of the side of a triangle are joined together to get four triangles. These four triangles are:

1. not equal to each other

2. congruent to each other

3. not congruent to each other

4. none of these

In the given figure, AB || CD || EF and E is the mid-point of side AD, then :

1. OE : OF = 1 : 3

2. OE = OF

3. OF = 2 x OE

4. CF = FB

In rhombus PQRS; A, B and C are mid-points of sides PQ, QR and RS respectively. If ∠P = 60°, the angle PQR is equal to:

1. 60°

2. 90°

3. 120°

4. none of these