Metamath Proof Explorer


Theorem abs2sqlei

Description: The absolute values of two numbers compare as their squares. (Contributed by Paul Chapman, 7-Sep-2007)

Ref Expression
Hypotheses abs2sqlei.1
|- A e. CC
abs2sqlei.2
|- B e. CC
Assertion abs2sqlei
|- ( ( abs ` A ) <_ ( abs ` B ) <-> ( ( abs ` A ) ^ 2 ) <_ ( ( abs ` B ) ^ 2 ) )

Proof

Step Hyp Ref Expression
1 abs2sqlei.1
 |-  A e. CC
2 abs2sqlei.2
 |-  B e. CC
3 1 absge0i
 |-  0 <_ ( abs ` A )
4 2 absge0i
 |-  0 <_ ( abs ` B )
5 1 abscli
 |-  ( abs ` A ) e. RR
6 2 abscli
 |-  ( abs ` B ) e. RR
7 5 6 le2sqi
 |-  ( ( 0 <_ ( abs ` A ) /\ 0 <_ ( abs ` B ) ) -> ( ( abs ` A ) <_ ( abs ` B ) <-> ( ( abs ` A ) ^ 2 ) <_ ( ( abs ` B ) ^ 2 ) ) )
8 3 4 7 mp2an
 |-  ( ( abs ` A ) <_ ( abs ` B ) <-> ( ( abs ` A ) ^ 2 ) <_ ( ( abs ` B ) ^ 2 ) )