tolong dibantu gan, khusus yg a nya aja

Segitiga ABC
AB = AC = 8cm
sudut A = 80°
Sudut B = sudut C =½ (180° - 80°)
= ½*100 = 50°

[tex]BC = 2 \times ( \frac{Cos 50}{AC}) \\ BC = 2 \times ( \frac{Cos 50}{8 \: cm}) \\ BC = ( \frac{Cos 50}{4 \: cm})[/tex]