[tex]Complementul\ unui\ unghi\ reprezinta\ 90^o -a \ (a\ este\ masura\ ungh.)[/tex]
[tex]a= \frac{25}{100}\cdot(90^o-a)= \frac{90}{4}- \frac{a}{4}\longrightarrow \frac{90^o-a}{4}= \frac{4a}{4} \ (amplificam\ cu\ 4\ ) [/tex]
[tex]\longrightarrow90^o-a=4a \longrightarrow90^o=5a\rightarrow \boxed{\boxed{a=18^o}}[/tex]
