Question

Find the diagonal of a cube if its side equals 5.

Answer 1

\( 5 \times \sqrt{3} \)

Answer 2

The longest diagonal of the cube!

Answer 3

5^2+5^2=2*25=50=5sqrt(2)

25+5sqrt(2)=3*5^2=75=5sqrt(3)

Answer 4

\[3\sqrt{5}\]

Answer 5

The answer is 5*sqrt(3), really we are, if we draw the cube, applying pythagorean theorm twice

Answer 6

8.66

Answer 7

you are ?

Answer 8

@Lagrange

Answer 9

yeah@FoolForMath

Answer 10

you dont believe me

Answer 11

I am incredulous without proof :P

Answer 12

lol, I know the proof.

Answer 13

Haven't I posted the same answer before ? :)

Answer 14

The line from D to B in the diagram completes the triangle DCB, which has a right angle at C. Thus, by Pythagoras' Theorem: (DB)^2=(DC)^2+(CB)^2=5^2+5^2=50=5sqrt(2)

Answer 15

Now consider the triangle ADB