Answer:

Step-by-step explanation:
Poorly formatted question; The complete question requires that we prove that 
When
and
We have:

Rewrite as:

Factorize

Rewrite as:

Factor out 1 + x

Multiply both sides by 

Integrate both sides

Rewrite as:

Integrate the left-hand side

Integrate the right-hand side

implies that: 
So:
becomes

This gives:



The equation
becomes


Take tan of both sides
--- Proved
Answer:
the missing angle is 130
Step-by-step explanation:
180-50=130
the right answer is first one
Answer:
Interest Charged = $80
Total payback = $480
Step-by-step explanation:
According to the scenario, computation of the given data are as follows,
Present Value (PV) = $400
Time period (n) = 4 years
Interest rate (r) = 5%
So, we can calculate the future value(FV), by using following formula,
FV = PV ( 1 + n × r)
By putting the value, we get
FV = $400 ( 1 + 4 × 0.05)
= $480
Hence total amount she has to pay back = $480.
Interest charged = FV - PV
= $480 - $400
=$80