That is a 30 60 90 triangle.
Read about those here: http://www.1728.org/trig2.htm
The intersected arc is the arc opposite the angle in question, here arc ABE.
Answer: ABE, last choice
Answer:
Step-by-step explanation:
Remark
This is an arithmetic series. Each term differs by 6 from the previous one.
Givens
a1 = 21
d = 6
Formula
a_n = a1 + (n - 1)*d
Sample
Try it.
Let's let n = 3 which we have the answer for.
a_3 = 21 + (3-1)*6
a_3 = 21 + 2 * 6
a_3 = 21 + 12
a_3 = 33
That's exactly what the 3rd term is.
1) Dimensiones of the cardboard:
length: 10 inches
width: 8 inches
2) dimensions of the squares cut
length: x
width: x
3) dimensions of the box:
length of the base = 10 - 2x
width of the base = 8 - 2x
height = x
4) Volume of the box
V = (10 - 2x) (8 - 2x) x = x [80 - 20x - 16x + 4x^2] = x [ 80 - 36x + 4x^2 ] =
V = 80x - 36x^2 + 4x^3
5) Maximum volume => derivative of V, V' = 0
V' = 80 - 72x + 12x^2 = 0
6) Solve the equation
Divide by 4 => 3x^2 - 18x + 20 = 0
Use the quadratic formula: x = 1.47 and x = 4.53 (this is not valid)
So, the answer is the option C. 1.5 inches.
Hmmm what is now discounted? well, let's assume it sells normally for 499 and is discounted today at 25%, how much is that?
well, if we take 499 to be the 100, how much is 25%?

now, applying the sales tax to the discounted price.
if we take 374.25 to be the 100%, how much is 6.5%?

so, the total cost will then be 374.25 + t.