It's annuity problem
To solve your question use the formula of the present value of annuity ordinary which is
Pv=pmt [(1-(1+r)^(-n))÷r]
Pv present value?
PMT yearly payments 18000
R interest rate 0.09
N time 20 years
So
Pv=18,000×((1−(1+0.09)^(−20))÷(0.09))
pv=164,313.82
For this case, we have that by definition, the area of a triangle is given by:

where:
b: It's the base
h: It's the height
In this case we have:

Substituting:

Answer:

Complete Question
The complete question is shown on the first uploaded image
Answer:
The value is 
Step-by-step explanation:
From the diagram we can obtain the the height of T as follows
