Answer:The length of AC to one decimal place in the trapezium is 18.1 cm
Step-by-step explanation: Using Pythagoras theorem, we can find the length AC
Pythagoras theorem
c² = a² + b²
Therefore, draw a line from the point B to the line AD and call it line BX.
BX ║ CD
Therefore,
16² - 7² = BX²
256 - 49 = BX²
BX² = 207
BX = √207
BX = 14.3874945699
BX = 14.4 cm
Therefore,
11² + 14.4² = AC²
121 + 207.36 = AC²
AC = √328.36
AC = 18.120706388
AC = 18.1 cm