<h3>
Answer: A. 18*sqrt(3)</h3>
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Explanation:
We'll need the tangent rule
tan(angle) = opposite/adjacent
tan(R) = TH/HR
tan(30) = TH/54
sqrt(3)/3 = TH/54 ... use the unit circle
54*sqrt(3)/3 = TH .... multiply both sides by 54
(54/3)*sqrt(3) = TH
18*sqrt(3) = TH
TH = 18*sqrt(3) which points to <u>choice A</u> as the final answer
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An alternative method:
Triangle THR is a 30-60-90 triangle.
Let x be the measure of side TH. This side is opposite the smallest angle R = 30, so we consider this the short leg.
The hypotenuse is twice as long as x, so TR = 2x. This only applies to 30-60-90 triangles.
Now use the pythagorean theorem
a^2 + b^2 = c^2
(TH)^2 + (HR)^2 = (TR)^2
(x)^2 + (54)^2 = (2x)^2
x^2 + 2916 = 4x^2
2916 = 4x^2 - x^2
3x^2 = 2916
x^2 = 2916/3
x^2 = 972
x = sqrt(972)
x = sqrt(324*3)
x = sqrt(324)*sqrt(3)
x = 18*sqrt(3) which is the length of TH.
A slightly similar idea is to use the fact that if y is the long leg and x is the short leg, then y = x*sqrt(3). Plug in y = 54 and isolate x and you should get x = 18*sqrt(3). Again, this trick only works for 30-60-90 triangles.
Represent the unknows with n and d.
Then n+d = 44 (# of coins)
and
$0.05n + $0.10d = $3.10 (value of coins)
Solving the first equation for n, we get n = 44-d. Subst. 44-d for n in the 2nd equation:
0.05(44-d) + 0.10d = 3.10
Then 2.20 - 0.05d + 0.10d = 3.10, or
2.20 + 0.05d = 3.10, or 0.05d = 0.90. Solving for d,
0.90
d = -------- = 18
0.05
There are 18 dimes and 44-18 nickels. How many nickels is that? ;)
2x^2 + 5x + 2 = 0
(x + 2)(2x + 1) = 0
x = -2 x = - 1/2
Letter C
Answer=
y=-3+3
y=0
the sum of -3+3 is zero.