In ΔABC, AB = 3, BC = 4, B = π/3. AFlati lungimea laturii AC

Răspuns :

AC²=AB²+BC²-2AB·BC·cosB=9+16-2·3·4·1/2=25-12=13
AC=√13 cm
AC la patrat = AB la patrat + BC la patrat-2× AB×BC×cos B = 9+16 -2×3×4×cos60 de grade= 25-2×3×4×1/2=25-3×4=25-12=13.
AC la patrat=13=> AC = radical din 13