Answer:

Step-by-step explanation:
Given:
The above triangle
Required
Solve for AB in terms of a, b and angle C
Considering right angled triangle BOC where O is the point between b-x and x
From BOC, we have that:

Make h the subject:

Also, in BOC (Using Pythagoras)

Make
the subject

Substitute
for h
becomes


Factorize

In trigonometry:

So, we have that:

Take square roots of both sides

In triangle BOA, applying Pythagoras theorem, we have that:

Open bracket

Substitute
and
in 


Open Bracket

Reorder

Factorize:

In trigonometry:

So, we have that:


Take square roots of both sides

Not sure if this is what you need
Answer:
480 Litres
Step-by-step explanation:
Percentage increase = 20% × 400
New value =
400 + Percentage increase =
400 + (20% × 400) =
400 + 20% × 400 =
(1 + 20%) × 400 =
(100% + 20%) × 400 =
120% × 400 =
120 ÷ 100 × 400 =
120 × 400 ÷ 100 =
48,000 ÷ 100 =
480