Answer:α
=
71
°
:
explain:
From trigonometry we have:
cos
α
=
7
21
7
=
21
cos
(
α
)
and:
α
=
a
r
c
cos
(
7
21
)
=
70.5
≈
71
∘
The answer is 343 if you add all together:)))
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
