In ΔABC, BC = 4 centimeters, m∠B = m∠C, and m∠A = 20°. What is AC to two decimal places?A.9.32 centimetersB.10.01 centimetersC.11.52 centimetersD.12.09 centimeters

m<A = 20°
m<B = m<C = 80°

Law of Sines , in any triangle we have
a/sin A = b/sin B = c/sin c

4/sin20 = AC/sin80 = AB/sin80

now we can solve AC

4/sin20 = AC/sin80
AC = 4 (sin80)/ sin20
AC = 4(0.98) / (0.34)
AC = 3.92 / 0.34
AC = 11.52

answer

C.11.52 centimeters