Question

In a quadrilateral ABCD, $\angle$A = 90${}^o$ and AB = BC = CD = DA, then ABCD is a ?

• A. parallelogram
• B. rectangle
• C. square
• D. none of these

Answer 1

Answer: (C)

square

If all sides are equal,
$AB=BC=CD=DA$ and one angle is $\angle A={90}^o$
then all angles are also becomes ${90}^o$ ,
$\angle A$ = $\angle B$ = $\angle C$ = $\angle D$ = ${90}^o$
Then the quadrilateral is square.