Is this correct? mathswatch won't give me full marks though i am sure it is?

9514 1404 393

  AD = 37.77 m

Step-by-step explanation:

Your premise is incorrect. Angle ECD is about 42.88°, found using the law of cosines.

  ∠ECD = arccos((EC²+DC²-ED²)/(2·EC·DC))

  ∠ECD = arccos(765/1044) ≈42.88°

The rest of the work is correct:

  AC = AB×sin(81°)/sin(42.88°) ≈ 66.77 m

  AD = AC - DC = 66.77 m - 29 m

  AD ≈ 37.77 m

step-by-step explanation:

see explanation

step-by-step explanation:

since the sequence is geometric there is a common ratio r between consecutive terms, that is

r = 4 ÷ - 2 = - 2

r = - 8 ÷ 4 = - 2

r = 16 ÷ 8 = - 2

the next term - 13 must be incorrect as it should be - 32 for the sequence to be geometric.

the first 4 terms are therefore geometric with common ratio r = - 2