Answer:

Step-by-step explanation:
![\cos(2x) = \cos^2 x-\sin^2 x = 1-2\sin^2 x \\ \\ \cos(x) = 1-2\sin^2 (\frac{x}{2}) \\ \\ \Rightarrow \sin^2 (\frac{x}{2}) = \dfrac{1-\cos(x)}{2}\\ \\ \sin(\frac{x}{2}) = \pm \sqrt{\dfrac{1-\cos(x)}{2}},\quad x\in [\frac{3\pi }{2},\pi] \Rightarrow \frac{x}{2}\in [\frac{3\pi}{4},\frac{\pi}{2}]\\ \\ \Rightarrow \sin(\frac{x}{2}) > 0 \Rightarrow \sin(\frac{x}{2}) = \sqrt{\dfrac{1-(-\frac{3}{5})}{2}} \Rightarrow \sin(\frac{x}{2}) = \sqrt{\dfrac{8}{10}}=\dfrac{2\sqrt 2}{\sqrt{10}} = \\ \\ =\dfrac{2\sqrt 5}{5}](https://tex.z-dn.net/?f=%5Ccos%282x%29%20%3D%20%5Ccos%5E2%20x-%5Csin%5E2%20x%20%3D%201-2%5Csin%5E2%20x%20%5C%5C%20%5C%5C%20%5Ccos%28x%29%20%3D%201-2%5Csin%5E2%20%28%5Cfrac%7Bx%7D%7B2%7D%29%20%5C%5C%20%5C%5C%20%5CRightarrow%20%5Csin%5E2%20%28%5Cfrac%7Bx%7D%7B2%7D%29%20%3D%20%5Cdfrac%7B1-%5Ccos%28x%29%7D%7B2%7D%5C%5C%20%5C%5C%20%5Csin%28%5Cfrac%7Bx%7D%7B2%7D%29%20%3D%20%5Cpm%20%5Csqrt%7B%5Cdfrac%7B1-%5Ccos%28x%29%7D%7B2%7D%7D%2C%5Cquad%20x%5Cin%20%5B%5Cfrac%7B3%5Cpi%20%7D%7B2%7D%2C%5Cpi%5D%20%5CRightarrow%20%5Cfrac%7Bx%7D%7B2%7D%5Cin%20%5B%5Cfrac%7B3%5Cpi%7D%7B4%7D%2C%5Cfrac%7B%5Cpi%7D%7B2%7D%5D%5C%5C%20%5C%5C%20%5CRightarrow%20%5Csin%28%5Cfrac%7Bx%7D%7B2%7D%29%20%3E%200%20%5CRightarrow%20%5Csin%28%5Cfrac%7Bx%7D%7B2%7D%29%20%3D%20%5Csqrt%7B%5Cdfrac%7B1-%28-%5Cfrac%7B3%7D%7B5%7D%29%7D%7B2%7D%7D%20%5CRightarrow%20%5Csin%28%5Cfrac%7Bx%7D%7B2%7D%29%20%3D%20%5Csqrt%7B%5Cdfrac%7B8%7D%7B10%7D%7D%3D%5Cdfrac%7B2%5Csqrt%202%7D%7B%5Csqrt%7B10%7D%7D%20%3D%20%5C%5C%20%5C%5C%20%3D%5Cdfrac%7B2%5Csqrt%205%7D%7B5%7D)
Answer:
A = √29
Step-by-step explanation:
The short of it is that ...
A² = 2² + 5² = 29
A = √29
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<u>Amplitude</u>
If you expand the second form using the sum-of-angles formula, you get ...
Asin(ωt +φ) = Asin(ωt)cos(φ) +Acos(ωt)sin(φ)
Comparing this to the first form, you find ...
c₂ = 2 = Acos(φ)
c₁ = 5 = Asin(φ)
The Pythagorean identity can be invoked to simplify the sum of squares:
(Asin(φ))² + (Acos(φ))² = A²(sin(φ)² +cos(φ)²) = A²·1 = A²
In terms of c₁ and c₂, this is ...
(c₁)² +(c₂)² = A²
A = √((c₁)² +(c₂)²) . . . . . . . formula for amplitude
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<u>Phase Shift</u>
We know that tan(φ) = sin(φ)/cos(φ) = (Asin(φ))/(Acos(φ)) = 5/2, so ...
φ = arctan(c₁/c₂) . . . . . . . formula for phase shift*
φ = arctan(5/2) ≈ 1.19029 radians
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* remember that c₁ is the coefficient of the cosine term, and c₂ is the coefficient of the sine term.
Answer:
She should win approximately 30 times.
Step-by-step explanation:
Since the probability of winning is 3/8, we multiply 3/8 with 80 to get 30.