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Snezhnost [94]
2 years ago
5

Review the proof of the identity cos(π − A) = −cosA.

Mathematics
2 answers:
Annette [7]2 years ago
6 0

Answer:

error in step 1

Step-by-step explanation:

well where is does the step not make sense?

remember cos(pi) = -1 and sin(pi)=0

that means step 1 is strange... it didn't distribute properly

it should have been:

cos(pi) - cos(A)

hope that helps! ^-^

Anestetic [448]2 years ago
5 0

Answer: Step 1 on EDGE2020

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Points H and F lie on circle c What is the length of line segment GH?
Nina [5.8K]

Answer:

6 units

Step-by-step explanation:

Given: Points H and F lie on  circle with center C. EG = 12, EC = 9 and ∠GEC = 90°.

To find: Length of GH.

Sol: EC = CH = 9 (Radius of the same circle are equal)

Now, GC = GH + CH

GC = GH + 9

Now In ΔEGC, using pythagoras theorem,

(Hypotenuse)^{2} = (Base)^{2} +(Altitude)^{2} ......(ΔEGC is a right triangle)

(GC)^{2} = (GE)^{2} +(EC)^{2}

(GH + 9)^{2} = (9)^{2} +(12)^{2}

(GH )^{2} + (9)^{2} + 18GH = 81 + 144

(GH )^{2} + 81 + 18GH = 81 + 144

(GH )^{2} + 18GH = 144

Now, Let GH = <em>x</em>

x^{2} +18x = 144

On rearranging,

x^{2} +18 x - 144 = 0

x^{2} - 6x +24x + 144 = 0

x (x-6) + 24 (x - 6) =0

(x - 6) (x + 24) = 0

So x = 6  and x = - 24

∵ x cannot be - 24 as it will not satisfy the property of right triangle.

Therefore, the length of line segment GH = 6 units. so, Option (D) is the correct answer.

3 0
1 year ago
Read 2 more answers
In electrical engineering, the unwanted "noise" in voltage or current signals is often modeled by a Gaussian (i.e., normal) dist
vladimir1956 [14]

Answer:

Cov(X, Y) =0.029.

Step-by-step explanation:

Given that :

The noise in a particular voltage signal has a constant mean of 0.9 V. that is μ = 0.9V ............(1)

Also, the two noise instances sampled τ seconds apart have a bivariate normal distribution with covariance.

0.04e–jτj/10 ............(2)

Having X and Y denoting the noise at times 3 s and 8 s, respectively, the difference of time = 8-3 = 5seconds.

That is, they are 5 seconds apart,

τ = 5 seconds..............(3)

Thus,

Cov(X, Y), for τ = 5seconds = 0.04e-5/10

= 0.04e-0.5 = 0.04/√e

= 0.04/1.6487

= 0.0292

Thus, Cov(X, Y) =0.029.

5 0
1 year ago
Estimate the value of 9.9 squared x 1.79
Helen [10]
9.9^2X1.79
9.9^2=98.01
98.01X1.79=175.4379
7 0
2 years ago
Read 2 more answers
The lengths of text messages are normally distributed with an unknown population mean. A random sample of text messages is taken
anygoal [31]

Answer:

95% of the text messages have length between 23 units and 47 units.

Step-by-step explanation:

We are given the following in the question:

The lengths of text messages are normally distributed.

95% confidence interval:

(23,47)

Thus, we could interpret the confidence interval as:

About 95% of the text messages have length between 23 units and 47 units.

By Empirical rule for a normally distributed data, about 95% of data lies within 2 standard deviations of mean , thus we can write:

\mu - 2\sigma = 23\\\mu +2\sigma = 47\\\Rightarrow \mu = 35\\\Rightarrow \sigma = 6

Thus, the mean length of text messages is 23 units and standard deviation is 6 units.

8 0
1 year ago
Read 2 more answers
Find the value of cosAcos2Acos3A...........cos998Acos999A where A=2π/1999
Lady bird [3.3K]
Hello,

Here is the demonstration in the book Person Guide to Mathematic by Khattar Dinesh.

Let's assume
P=cos(a)*cos(2a)*cos(3a)*....*cos(998a)*cos(999a)
Q=sin(a)*sin(2a)*sin(3a)*....*sin(998a)*sin(999a)

As sin x *cos x=sin (2x) /2

P*Q=1/2*sin(2a)*1/2sin(4a)*1/2*sin(6a)*....
         *1/2* sin(2*998a)*1/2*sin(2*999a) (there are 999 factors)
= 1/(2^999) * sin(2a)*sin(4a)*...
     *sin(998a)*sin(1000a)*sin(1002a)*....*sin(1996a)*sin(1998a)
 as sin(x)=-sin(2pi-x) and 2pi=1999a

sin(1000a)=-sin(2pi-1000a)=-sin(1999a-1000a)=-sin(999a)
sin(1002a)=-sin(2pi-1002a)=-sin(1999a-1002a)=-sin(997a)
...
sin(1996a)=-sin(2pi-1996a)=-sin(1999a-1996a)=-sin(3a)
sin(1998a)=-sin(2pi-1998a)=-sin(1999a-1998a)=-sin(a)

So  sin(2a)*sin(4a)*...
     *sin(998a)*sin(1000a)*sin(1002a)*....*sin(1996a)*sin(1998a)
= sin(a)*sin(2a)*sin(3a)*....*sin(998)*sin(999) since there are 500 sign "-".

Thus
P*Q=1/2^999*Q or Q!=0 then
P=1/(2^999)

       








7 0
1 year ago
Read 2 more answers
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