Here ABC is a right angle triangle because 1 angle is 90°
BY ASP,
90+56+ angle CAB=180
angle CAB=34°
rounded to nearest = 30°
sin A =opp/hyp
sin 30 = 7/x
1/2=7/x
x=14
rounding to nearest 10
14 =10
AB=10
By Pythagoras Theorem,
AB²=BC²+AC²
AC²=AB²-BC²=10² - 7²
100- 49 = 51
AC=root 51