Question

ength of diagonals of a cube of side a cm is a)√3 a cm b)√2a cm c)√5 a cm d)√a cm

Answer 1

Step-by-step explanation:

As the diagonals  of a square are perpendicular bisector of each other applying Pythagoras theorem in △ABC

H2=P2+B2

a= side of the square 

AB=AC=a

AC2=a2+a2=2a2

AC=2a

In △ACD

AC2+CD2=AD2

AD=2a2+a2=3a which is the diagonal 

3a=152

a=56