The effective rate is calculated in the following way:

where r is the effective annual rate, i the interest rate, and n the number of compounding periods per year (for example, 12 for monthly compounding).
our compounding period is 2 since the bank pays us semiannually(two times per year) and our interest rate is 8%
so lets plug in numbers:
Answer:
∠ U = 22.62°
Step-by-step explanation:
We can use the trigonometric expression to find ∠U by using the ratio:
sin(θ) = opposite/ hypotenuse
=> sin ∠U = 7.5/ 19.5
=> ∠ U =
( 7.5/ 19.5)
∴ ∠ U = 22.619° ≈ 22.62°
L=2W+3, A=LW, using L from the first in the second gives you:
A=(2W+3)W
A=2W^2+3W, and we are told A=90 so
2W^2+3W=90
2W^2+3W-90=0
2W^2-12W+15W-90=0
2W(W-6)+15(W-6)=0
(2W+15)(W-6)=0, since W>0 for all real possibilities,
W=6ft, and since L=2W+3
L=15ft
So the pool will be 6 ft wide by 15 ft long.