Réponses

  • Utilisateur Brainly
2013-01-09T21:47:02+01:00

1+(sinx/cosx)²=(sinx²+cosx²)/cosx²=1/cosx² CQFD

2013-01-09T21:48:48+01:00

J'ai remplacer "a" par "x"

 

1+tan²x

=1+ (tan â)²

=1/1+(sin â)²/(cos â)²

=(cos â)²/(cos â)² + (sin â)²/(cos â)²

=(cos â)² + (sin â)²/(cos â)²

=1/(cos â)²

=1/cos²a