Răspuns:
[tex]a) sinB+cosB=sinC+cosC\\[/tex]
[tex]\frac{AC}{BC}+\frac{AB}{BC}=\frac{AB}{BC}+\frac{AC}{BC}[/tex] "Adevarat"
[tex]b) cosB+sinC=sinB+sinC[/tex]
[tex]\frac{AB}{BC}+\frac{AC}{BC}=\frac{AC}{BC}+\frac{AB}{BC}[/tex] "Adevarat"
[tex]c) tgB+tgC=ctgB+ctgC[/tex]
[tex]\frac{AC}{AB}+\frac{AB}{AC}=\frac{AB}{AC}+\frac{AC}{AB}[/tex]"Adevarat"
Am lucrat in triunghiul din imagine:
