👤

cum verific aceasta egalitate?


Cum Verific Aceasta Egalitate class=

Răspuns :

a. aplicam formula

[tex]sin(a+b)=sin a\times cosb+sinb\times cosa\\\\sin(90+x)=sin90\times cosx+sinx\times cos90=cosx[/tex]

Precizam ca : sin90=1 si cos90=0

b. aplicam formula

[tex]cos(a+b)=cosa\times cosb-sina\times sinb\\\\cos(90+x)=cos90\times cosx-sin90\times sinx=0-sinx=-sinx[/tex]