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Serggg [28]
3 years ago
6

How do you do... cos2x-sin2x=1-2sin2x

Mathematics
1 answer:
Bess [88]3 years ago
3 0
sin (2 \alpha) =2\cdot sin  \alpha \cdot cos  \alpha \\cos(2 \alpha )=1-2sin^2  \alpha \\-------------------- \\cos2x-sin2x=1-2sin2x\\cos2x+sin2x=1\\1-2sin^2x+2sinx\cdot cosx=1\\-2sinx(sin x-cosx)=0\\ -2sinx=0\ \ \ \ or\ \ \ \ sinx-cosx=0\\\\1)\ -2sinx=0\ \ \Leftrightarrow\ \ sinx=0\ \ \Leftrightarrow\ \ x_1=k \pi \ \ and\ \ k\in I\\2)\ \ sinx-cosx=0\ \ \Leftrightarrow\ \ sinx=cosx\ /:cosx\ \ \ \ \ \wedge\ \ \ \  cos x \neq 0\\tanx=1\ \ \Leftrightarrow\ \ x_2= \frac{ \pi }{4} +k \pi \ \ and\ \ k\in I
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How do you know when to put an open or closed circle when graphing inequalities?
Marina CMI [18]
An open circle means not equal to. So, if your equation is x < 4, You would put an OPEN circle at four because it can't equal four.
3 0
3 years ago
Hi, can you help me answer this question please, thank you!
matrenka [14]

It is given that the sample size is 17.

So degrees of freedom is 16.

The confidence level is 80%.

Use the t table or a tool to find the critical t value as below:

The one tail t value for 80 percent confidence is 0.865 using t table.

So the critical value is 0.865.

8 0
1 year ago
Determine the type and number of solutions of −4x2 − 3x + 7 = 0.
Kaylis [27]

Answer:

Step-by-step explanation:

You have to use the discriminant for this. If the quadratic is -4x^2-3x+7, then

a = -4, b = -3, and c = 7. The formula for finding the discriminant is

D=b^2-4ac which comes from the quadratic formula, but without the square root sign. Filling in:

D=(-3)^2-4(-4)(7) which simplifies down to

D = 9 + 112 so

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7 0
3 years ago
A rock is thrown upward at a speed of 69 mph when the rock reaches its peak how fast is it going and what is the magnitude and a
aleksandrvk [35]
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6 0
3 years ago
Find the sum.
hichkok12 [17]

Answer:

C - 19/24

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Take the fractions and put the denominators into a common factor

\frac{1}{3}+ \frac{1}{3}+ \frac{1}{8}

\frac{8}{24}+ \frac{8}{24}+ \frac{3}{24}

Add Numerators Across

\frac{16}{24}+ \frac{3}{24}

\frac{19}{24}

8 0
3 years ago
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