11 Plus Exams Forum

Hello, can you advise if my son's answer to this question is also correct?

Read the following statement.

'A four-sided shape with opposite sides that are parallel and of equal length.'

What shape is being described?

DS answer is a square but Bond answer sheet says Rhombus. Since no reference is made to angles, isn't a square equally valid?

Hi,

A square is a rhombus with right angles. So I would say your child is right.

Square is "a" correct answer but not "the" correct answer. An infinite number (rhombus) shapes fit the description, and only one of them is a perfect square. In other words, it's because no reference is made to angles that the answer is rhombus.

If the question was "a four sided shape with parallel sides and with every angle a right angle", "square" would likewise not be "correct".

Not a very good question IMHO, though - more a test of pedantic tendencies than intelligence.

Mike

Thanks for your replies. I'll let this one pass because DS will never concede the point, semantics or not.

Well, I think he has a point. I vaguely recall coming across this question or something very like it in the 10-min books and Miss 1880 said square as well. I gave her the mark - I think it's a stupid question...

Mike

My DD says: " Both answers are correct. This is because, technically, a square is a type of rhombus. If you stand a square on one corner and squash it at the two corners that stick out on the sides, you get a rhombus. So, a rhombus is a squashed square."

2 parallel sides which are equal in length necessarily give you a parallelogram when you add 2 more sides.

If all four sides are equal in length, then you get a special parallelogram called a rhombus.

If all four angles are equal, then you get a special rhombus called a square.