If you have a calculator, you can use the inverse cos " cos⁻¹ " key. Many upper level books write that as Arccos so as not to confuse you with a negative exponent. We do that because if you take the cosine of any angle, and then the inverse cosine of any angle, it leads you back to the original angle. Think of it as a big "UNDO" button.
To one decimal place, that result is 61.6 degrees.
We divide the total sum of the angles by 20

=18 sides
D is correct because the 48 quart * 4cup/1quart*8ounce/1Cup=1536 fl .oz
<h3>
Answer: 5 cm</h3>
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Explanation:
Recall that the range for cosine is from -1 to 1, including both endpoints. The smallest cosine value is what we're after, since we want the height to be as small as possible (to allow the blade be closest to the table).
Effectively, this means we replace the cos(x) with -1 so that it's as small as possible. Then we compute to get:
20*cos(x)+25
20*(-1) + 25
-20 + 25
5
The height of the fan tip is 5 cm when it is the closest to the table.
Side note: On the flip side, the furthest away the fan tip can get is 20*(1) + 25 = 45 cm. Therefore, the range of y values is 
Answers:
x=22
x+4=26
6x=132
Explanation:
We learned from the question that all of the angles in a triangle add up to 180 degrees.
180=angle+angle+angle
When we plug in the values that the question gives us for the angles, we get this equation:
180=x+6x+(x+4)
After solving this equation, we get 22 as the value of x (The process of solving that equation is in the picture attached).
To solve for (x+4), we plug in the value of x, which is 22 and add 4.
(x+4)
=(22+4)
=26
And finally, to solve for 6x, we plug in 22 again:
6x
=6*22
=132
Hope this helps!