If the diagonals of a quadrilateral PQRS bisect each other at right angles, then the quadrilateral PQRS must be a

1. parallelogram

2. rectangle

3. rhombus

4. square

Which of the following statement is true for a parallelogram?

1. Its diagonals are equal.

2. Its diagonals are perpendicular to each other.

3. The diagonals divide the parallelogram into four congruent triangles.

4. The diagonals bisect each other.

If the diagonals of a square ABCD intersect each other at O, then △OAB is

1. an equilateral triangle

2. a right angled but not an isosceles triangle

3. an isosceles but not right angles triangle

4. an isosceles right angled triangle.

The diagonals AC and BD of a parallelogram ABCD intersect each other at the point O. If ∠DAC = 32° and ∠AOB = 70°, then ∠DBC is equal to

1. 24°

2. 86°

3. 38°

4. 32°