For the given triangle, the tan of angle A equals C. 
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Step-by-step explanation:
Step 1; In the given triangle, the opposite side has a length of 15 units, the adjacent side has a length of 36 units while the hypotenuse of the triangle measures 39 units. To calculate the tan of angle A we divide the opposite side's length by the adjacent side's length.
cos A = 
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Step 2; The opposite side's length = 15 units,
The adjacent side's length = 36 units.
cos A = 
, dividing the numerator and the denominator by 3, we get
cos A = , which is option C.
Answer: Irrational
I'm going to write 'x' in place of "square root of 2" just to save time. Let's consider the possibility that 7-x is rational. I'm going to show there's a contradiction which ultimately concludes that the expression is irrational.
If 7-x was rational, then 7-x = p/q for some integers p,q with q being nonzero. Solve for x to get
7-x = p/q
-x = (pq) - 7
x = -(p/q) + 7
x = 7 - (p/q)
x = (7q/q) - (p/q)
x = (7q-p)/q
So if 7-x were rational, then this forces x to be rational because 7q-p is an integer over q (also an integer). The format is rational = integer/integer. But this is where the contradiction lies. Remember that x is standing in place for "square root of 2", which is an irrational number. There is no way to write sqrt(2) as a ratio of two integers. So x cannot be both rational and irrational at the same time.
Therefore, 7-x must be irrational making 7-sqrt(2) to be irrational as well.
note: sqrt is shorthand for "square root"
another note: adding any rational number to an irrational number will always result in an irrational number.
Answer: x ~34.31 (rounded)
(5 / 3) * PI = 300 degrees
Sector area = (central angle (degrees) / 360) * PI * radius^2
Sector area = (300 / 360) * 3.14 * 36
Sector area = (5/6) * 3.14 * 36
Sector area = 30 * 3.14
Sector area = 94.2 square feet
Source: http://www.1728.org/radians.htm
X is how much it costs for one hour, so when you multiply it by 3 1/2, you get the amount of money charged for 3 and a half hours.
