Maths homework - The Sine rule

I have to do questions 4 and 5 on Homework 22G in the GCSE Maths 2 tier-higher for AQA B Homework book and I would like some help on them please.

Question 4: In triangle ABC, the angle at A is 58 degrees, the side AB is 20cm and the side BC is 18cm. Find two possible values of the side AC.

Question 5:
To calculate the length of a submarine Mervyn stands on a cliff 60m high and measures the angle of depression of both ends of the boat. The information is shown in the diagram.
a Find the value of the angle DAB.
b Use trigonometry to calculate the length AB.
c Use the sine rule to find the length BC.

I have to do questions 4 and 5 on Homework 22G in the GCSE Maths 2 tier-higher for AQA B Homework book and I would like some help on them please.

Question 4: In triangle ABC, the angle at A is 58 degrees, the side AB is 20cm and the side BC is 18cm. Find two possible values of the side AC.

Question 5:
To calculate the length of a submarine Mervyn stands on a cliff 60m high and measures the angle of depression of both ends of the boat. The information is shown in the diagram.
a Find the value of the angle DAB.
b Use trigonometry to calculate the length AB.
c Use the sine rule to find the length BC.