a-numarul initial
2a + [tex] \frac{a}{4} [/tex] = a+25 /*4
8a + a = 4a+100
5a=100
a=20
2. AB=AC => [tex] BC^{2} [/tex] = [tex] AB^{2} [/tex] + [tex]AB^{2} [/tex]
[tex]AB^{2} [/tex]+[tex] 3^{2} [/tex]=2[tex]AB^{2} [/tex]
[tex]AB^{2} [/tex]=9 => AB=3 cm
[tex]BC^{2} [/tex]=[tex] 3^{2} [/tex]+[tex]3^{2} [/tex] => BC =3[tex] \sqrt{2} [/tex] cm