9.This is because it goes through the whole circle passing through the centre point. at the full width
The rest are pretty easy. I'm sure you can manage. Good luck!
R = 8 tan(x) sec(x)
In order to solve this, we are going to use the following:
r = sqrt(x^2 + y^2) //but in this case, we don't need this.
tan(x) = Y / X
X = r cos(x)
Y = r sin(x)
<span>(r cos x)^2 = 8(r sin x)</span>
x^2 = 8y
He is not correct, any number 5 or greater rounds the number up.
The speed of the dragonfly would be 7 because 7 rounds 9 to 10 making 6 a 7.
Total sales = $3600
Commission earned on $3600 = $576
Commission rate can be calculated as = 
= 16%
Hence, commission rate is 16%